Oleh: blackturtle36 | Februari 3, 2014

Fitness-for-service assessment of unpiggable pipelines

Fitness-for-service assessment of unpiggable pipelines

Advanced ultrasonic in-line inspection tools provide accurate, repeatable,100 per cent coverage data that can be used to manage pipeline reliability.

Pipeline operators have long been aware of the need to manage and maintain the integrity of their systems. Recent advances and proven deployment of compact, highly accurate ultrasonic inspection tools for unpiggable and difficult-to-inspect pipelines, in addition to engineering assessment, allow operators to analyse and make decisions that affect continuing reliability.

Quest Integrity Group has developed a number of leading-edge solutions for the inspection and assessment of unpiggable pipelines. InVista is an ultrasonic, fully self-contained, free flowing in-line inspection tool. Unlike other systems, it provides direct measurement of anomaly characteristics for superior pipeline integrity assessment.

The tool detects internal and external corrosion in addition to the dimensional change in difficult configurations, including 1D bends. The tool is easily launched and bi-directional, and is designed to provide high-resolution measurement data of axial position, geometry, and wall thickness.

Fitness-for-service assessment

Fitness-for-service assessment is a multi-disciplinary approach to evaluate structural components to determine if they are fit for continued service. Pipelines may contain flaws or other damage, or may be subject to more severe operating conditions than the original design anticipated. Quest Integrity Group’s LifeQuest pipeline assessment solution uses API 579-1/ASME FFS-1 fitness-for-service methodology to deliver an assessment of the pipeline for continued operation at defined maximum allowable operating pressure. An evaluation of remaining life and/or inspection intervals may also be part of such an assessment.

sumber: http://pipelinesinternational.com/news/fitness-for-service_assessment_of_unpiggable_pipelines/053611/, diakses 3 Februari 2014

Pipeline corrosion, improper operations behind Qingdao blasts

China’s top work safety watchdog said on Thursday that pipeline corrosion causing oil leakage into the sewage network and poor work conduct led to the fatal explosions that rocked Qingdao City of east China’s Shandong Province late last year.

The blasts, which occurred on Nov. 22, left 62 people dead and 136 others injured, and caused economic losses of 750 million yuan (122.7 million U.S. dollars).

The major cause of the incident was corrosion that wore down the pipeline and made it break. Meanwhile, work on a sewage cover plate on the day of the accident used a hydraulic hammer that wasn’t explosion-proof, producing the sparks that triggered the blasts, said Huang Yi, spokesman for the State Administration of Work Safety (SAWS).

He said that the blasts have been identified as a “responsibility incident.” The investigation report has been sent to the cabinet for review.

Lack of responsibility in major hazards inspection and weak emergency response from both pipeline operator Sinopec and local government departments were also exposed through the incident, Huang said.

He added that disorderly municipal design at the work site also brewed security risks in that the oil pipeline was shared with the municipal sewage network and installed at a range too close to nearby buildings.

According to government data, China’s total domestic mileage of oil and gas pipelines stands at 102,000 km, with some of it having served for as long as 40 years. The old rusty pipelines, some intertwined with municipal networks, pose major risks.

A special government overhaul of nearly 3,000 petrochemical companies and oil storage facilities since Nov. 22 has revealed nearly 20,000 potential hazards, which are currently being treated, said Wang Haoshui, an SAWS inspector in charge of petrochemical work safety.

sumber: http://news.xinhuanet.com/english/china/2014-01/09/c_133031646.htm, diakses 3 Februari 2014

Oleh: blackturtle36 | Februari 3, 2014

Pipeline Inspection

Pipeline Inspection

In the United States, millions of miles of pipeline carrying everything from water to crude oil. The pipe is vulnerable to attack by internal and external corrosion, cracking, third party damage and manufacturing flaws. If a pipeline carrying water springs a leak bursts, it can be a problem but it usually doesn’t harm the environment. However, if a petroleum or chemical pipeline leaks, it can be a environmental disaster. More information on recent US pipeline accidents can be found at the, National Transportation Safety Board’s Internet site. In an attempt to keep pipelines operating safely, periodic inspections are performed to find flaws and damage before they become cause for concern.

When a pipeline is built, inspection personnel may use visual, X-ray, magnetic particle, ultrasonic and other inspection methods to evaluate the welds and ensure that they are of high quality. The image to the left show two NDT technicians setting up equipment to perform an X-ray inspection of a pipe weld. These inspections are performed as the pipeline is being constructed so gaining access the inspection area is not problem. In some areas like Alaska, sections of pipeline are left above ground like shown above, but in most areas they get buried. Once the pipe is buried, it is undesirable to dig it up for any reason.

So, how do you inspect a buried pipeline?

Have you ever felt the ground move under your feet? If you’re standing in New York City, it may be the subway train passing by. However, if you’re standing in the middle of a field in Kansas it may be a pig passing under your feet. Huh??? Engineers have developed devices, called pigs, that are sent through the buried pipe to perform inspections and clean the pipe. If you’re standing near a pipeline, vibrations can be felt as these pigs move through the pipeline. The pigs are about the same diameter of the pipe so they range in size from small to huge. The pigs are carried through the pipe by the flow of the liquid or gas and can travel and perform inspections over very large distances. They may be put into the pipe line on one end and taken out at the other. The pigs carry a small computer to collect, store and transmit the data for analysis. In 1997, a pig set a world record when it completed a continuous inspection of the Trans Alaska crude oil pipeline, covering a distance of 1,055 km in one run. Click here to read more about this record setting inspection.

Pigs use several nondestructive testing methods to perform the inspections. Most pigs use a magnetic flux leakage method but some also use ultrasound to perform the inspections. The pig shown to the left and below uses magnetic flux leakage. A strong magnetic field is established in the pipe wall using either magnets or by injecting electrical current into the steel. Damaged areas of the pipe can not support as much magnetic flux as undamaged areas so magnetic flux leaks out of the pipe wall at the damaged areas. An array of sensor around the circumference of the pig detects the magnetic flux leakage and notes the area of damage. Pigs that use ultrasound, have an array of transducers that emits a high frequency sound pulse perpendicular to the pipe wall and receives echo signals from the inner surface and the outer surface of the pipe. The tool measures the time interval between the arrival of a reflected echos from inner surface and outer surface to calculate the wall thickness.

On some pipelines it is easier to use remote visual inspection equipment to assess the condition of the pipe. Robotic crawlers of all shapes and sizes have been developed to navigate the pipe. The video signal is typically fed to a truck where an operator reviews the images and controls the robot.

sumber: http://www.ndt-ed.org/AboutNDT/SelectedApplications/PipelineInspection/PipelineInspection.htm, diakses 3 Febrauari 2014

Decommissioning, abandonment and removal off obsolete offshore installations

Abandonment options

The extremely high cost of decommissioning and removal off offshore installations led to the need to revise some of the national and international regulations adopted about 40 years ago. Such a revision covered, in particular, the requirement set by the Convention on the Continental Shelf (Geneva, 1958) and the United Nations Convention on the Law of the Sea (Montego Bay, 1982) to remove abandoned offshore installations totally. At present, a more flexible and phased approach is used. It suggests immediate and total removal of offshore structures (mainly platforms) weighing up to 4,000 tons in the areas with depths less than 75 m and after 1998 – at depths less than 100 m. In deeper waters, removing only the upper parts from above the sea surface to 55 m deep and leaving the remaining structure in place is allowed. The removed fragments can be either transported to the shore or buried in the sea. This approach considers the possibility of secondary use of abandoned offshore platforms for other purposes.

From the technical-economic perspective, the larger the structures are and the deeper they are located, the more appropriate it is to leave them totally or partially intact. In shallow waters, in contrast, total or partial structure removal makes more sense. The fragments can be taken to the shore, buried, or reused for some other purposes.

From the fisheries perspective, any options when the structures or their fragments are left on the bottom may cause physical interference with fishing activities. In these cases, the possibility of vessel and gear damages and corresponding losses does not disappear with termination of production activities in the area. Instead, abandoned structures pose the threat to fishing for many decades after the oil and gas operators leave the site. The obsolete pipelines left on the bottom are especially dangerous in this respect. Their degradation and uncontrolled dissipation over wide areas may lead to the most unexpected situations occurring during bottom trawling in the most unexpected places. At the same time, national and international agreements about the decommissioning and abandonment of offshore installations refer mostly to large, fixed structures like drilling platforms. The fate of underwater pipelines is still not affected by clear regulations.

Secondary use of offshore fixed platforms

The options of reusing abandoned platforms, their foundations, and other structures that are out of service have been actively discussed for the last 10 years.

An analysis of scientific potential of research stations permanently based on abandoned oil platforms in the Gulf of Mexico revealed several promising directions of marine research at such stations [Dokken, 1993; Gardner, Wiebe, 1993]. These include studying regulation of the marine populations and coral reproduction, making underwater observations, monitoring the sea level, and collecting oceanographic and meteorological information within the framework of international projects. Some other suggestions consider transformation of abandoned platforms into places for power generation using wind/wave and thermal energy [Rowe, 1993]. These platforms also could be used as bases for search and rescue operations or centers for waste processing and disposal [Side, 1992].

From the fisheries perspective, the most interesting projects are the ones aimed at converting the fixed marine structures into artificial reefs. Artificial reefs are known to be one of the most effective means of increasing the bioproductivity of coastal waters by providing additional habitats for marine life. They are widely and effectively used on the shelves of many countries.

The offshore structures can undoubtedly attract many species of migrating invertebrates and fish searching for food, shelter, and places to reproduce. In particular, observations in the Gulf of Mexico revealed a strong positive correlation between the amount of oil platforms, growing since the 1950s, and commercial fish catches in the region. It became one of the reasons to suggest the positive impact of offshore oil and gas developments on the fish populations and stock. Wide popularization of this fact led to the mass movement using the slogan “From rigs – to reefs” in the USA in the mid-1980s.

However, further analyses of the fishing situation in the Gulf of Mexico showed that the growth of the fish catch in this case was connected not with increasing the total stock and abundance of commercial species but with their redistribution due to the reef effect of the platforms. A critical point here was the use of static gear methods of fishing (e.g., lines and hooks) instead of trawl gears. Besides, the areas around the platforms became very popular places of recreational and sport fishing. This also made a significant contribution to the total catch volumes. Nothing similar was noted in the North Sea, where the number of oil platforms has also been growing since the 1960s. However, the total catch did not correlate with this growth at all and even decreased. This fact indicates the absence of any positive impact of the reef effect of oil platforms on the commercial fish catches in areas where the main way to fish is trawling.

At the same time, we should not forget about the danger that abandoned offshore oil platforms and their fragments pose to navigation and trawling fishing. With an abundance of such artificial reefs, this problem requires special regulations for negotiating the inevitable conflict of interests. One such regulatory program has been developed and applied in the USA in the Gulf of Mexico on the shelf of Louisiana [Pope et al., 1993]. It requires mapping the area to indicate the locations of platforms, underwater pipelines, and other structures left on the bottom. The program also includes monitoring, collecting data, developing a warning system, and other activities necessary to control the situation and ensure safety in the region.

Explosive activities

Complete or partial removal of steel or concrete fixed platforms that weigh thousands of tons is practically impossible without using explosive materials. Bulk explosive charges have been used in 90% of cases. This is very powerful, although short-term, impact on the marine environment and biota, which should not be neglected.

It is extremely difficult to get any reliable estimates of possible mortality of marine organisms, especially fish, during an explosive activity even if the initial data, such as the type of explosive, depth of the water, bottom relief, and others, are known. This large uncertainty is connected, in particular, with the high heterogeneity of fish distribution that strongly depends on specific features of fish schooling behavior. Calculations show that with a 2.5-ton (TNT equivalent) charge, the mass of killed fish will be about 20 tons during each explosion. At the same time, if, for example, a school of herring happens to get into that zone, the fish kill figure may be much higher [Side, Davies, 1989].

One of the few known observations of fish damage in zones of explosive activity was done in 1992 in the Gulf of Mexico near the shore of Louisiana and Texas [Gitschlag, Herczeg, 1994]. In order to remove over 100 fixed platforms and other structures, more than 12,000 kg of plastic charges were exploded. The amount of dead fish floating on the surface was visually recorded after the explosions. It totaled to about 51,000 specimens. The actual number of killed fish was undoubtedly higher because many specimens could not float to the surface or did not get in the zone of visual observation.

Whatever number of adult fish actually died during the explosions, it will hardly influence the total abundance of commercial species. Much more hazardous for the fish stock are explosive impacts on fish larvae and juveniles. The threshold of lethal impacts for the younger organisms weighing up to several grams is tens of times lower than that for adult specimens [Yelverton et al., 1975; Side, 1992]. Thus, the zone of mortality of fish at the early stages of development is respectively wider. The quantitative estimates of possible effects at the populational level are even more complicated because of the absence of corresponding data and methods. Nevertheless, enough evidence exists to enforce strict regulations of explosive activities and to forbid them in areas and in seasons of spawning and fry development of commercial fish.

Removal of the offshore structures also decreases the number of habitats for structure-related fish. For example, in the mostly soft-bottom environment of the Gulf of Mexico, these structures provide hard substrates for marine organisms. The decline of stocks of reef fish observed in this region within the past decade can be connected, in particular, with elimination of over 400 oil-related structures that had served as an artificial habitat for marine life.

sumber: http://www.offshore-environment.com/abandonment.html, diakses 3 Februari 2014

Oleh: blackturtle36 | Februari 3, 2014

Commissioning of Submarine Pipeline Systems

Commissioning of Submarine Pipeline Systems

Operation and maintenance of High-pressure Petroleum Pipelines

Upon subsea pipelines installation and hook-up to the existing offshore extraction and processing platforms/facilities, the system shall be commissioned (i.e. starts normal design operating activities).

Preparations for operation shall be deemed complete when the plans and procedures described below would have been implemented. With the preparation completed and with approval given to start operation, the filling of the pipeline can occur and the pipeline can then be put into operation.

Pipelines shall not be considered ready to commence or recommence operation unless, as a minimum, the following typical check list has been completed:

  • The pipeline complies with the requirements of all relevant parts of AS 2885.1 (Pipelines – Gas and liquid petroleum Australian Standard).
  • The hydrostatic strength and leak test requirements have been achieved and documented.
  • The MAOP (Maximum Allowable Operating Pressure) has been established.
  • The welds of tie-ins to existing facilities, which have not been subjected to testing in accordance with 2nd bullet point, have been inspected by an approved non-destructive examination method.
  • Components have been tested for satisfactory operation. Where impractical, other appropriate inspection shall be carried out.
  • Operating, maintenance and emergency personnel have been trained.
  • The pipeline is cathodically protected as required by AS 2885.1.
  • Threat mitigation measures have been implemented in accordance with Section 3.4. of AS 2885.1.

Where a pipeline is to be placed in operation with a time delay, it shall meet the requirements of AS 2884.1. If the hydrostatic test fluid is allowed to remain in the pipeline, the test fluid shall either be dosed with a corrosion inhibitor or the pipeline filled with a fluid that inhibits corrosion, unless it can be demonstrated that such measures are not warranted.

Where the test fluid is removed, the pipeline shall be dried or purged, or both, with inert gas to produce moisture level that will not promote corrosion during the delay period.

Where the pipeline is left filled with fluid, precautions shall be taken to ensure that no damage is caused by overpressure due, for example, to thermal expansion effects. During the period between the hydrostatic test and the initial operation, the pipeline integrity shall be maintained in accordance with this Standard.

Corrective action shall be taken when an inspection reveals that unacceptable corrosion is occurring.

PURGING/CLEANING AND FILLING A PIPELINE – TYPICAL PROCEDURES

To bring a pipeline into service, the operating authority shall ensure that:

  • A pipeline is purged and filled in a safe manner;
  • Work is undertaken on a pipeline only when all relevant specifications have been complied with;
  • An approved procedure is developed specific to the pipeline and the nature of the fluid being purged, filled or commissioned;
  • The approved procedure is implemented during purging and filling or commissioning.

The above mentioned procedures shall address the following requirements:

  • The appropriate number, experience, training and induction of personnel involved in the procedure.
  • The level and control of the filling rate.
  • Controlling and monitoring the discharge of displaced fluids and venting of gases.
  • Limiting the mixing of fluids at their interface.
  • Controlling and minimizing the formation of explosive gaseous mixtures at the gas/air interface.
  • Removing unacceptable residues from the pipeline.
  • Continually discharging any static electricity generated to an effective earth.
  • A job hazard and safety analysis.
  • Minimization of hydrocarbon discharge.
  • Preventing the discharged fluid from causing unacceptable environmental effects such as damage to crops, excessive erosion, soil contamination or contamination of watercourses or bodies of water.

Filling a gas pipeline

Prior to filling a gas pipeline, a plan shall be prepared, which shall contain all relevant supporting calculations. When a pipeline is being purged of air by the use of gas, prior to filling, consideration shall be given to the safety and operational consequences of the formation of an explosive mixture at the gas/air interface.

A direct purge with gas may be used provided the approved procedures meet the conditions and requirements of AGA Operating Section Report Purging Principles and Practice, Catalogue No. XK0775.

During purging the gas should be released into one end of the pipeline in a controlled and continuous flow at an appropriate rate for the pipeline being purged. A slug of inert gas of sufficient length to separate the air from the gas to control the formation of an explosive mixture, may be released into the pipeline before the gas. Pigs or spheres may be used in some cases to reduce mixing at the interface and, therefore, reduce the volume of explosive mixture or reduce the volume of inert gas required.

Where the above conditions cannot be met or controlled for the duration of the purge, then the operating authority shall ensure that the approved procedure, using an alternative technique, purges the pipeline in a safe and efficient manner.

Filling a liquid petroleum pipeline

Prior to filling a liquid pipeline, a plan shall be prepared, which shall contain all relevant supporting calculations. The plan shall control the speed of the interface by applying appropriate back pressure at

the gas release point. Where air in a pipeline is to be displaced by a hydrocarbon liquid, a slug of appropriate liquid between spheres or batching pigs should separate the air and hydrocarbon liquid.

Where the slug in a pipeline is to be displaced by a hydrocarbon liquid, it shall be physically separated from the hydrocarbon liquid. The flash-point of the initial hydrocarbon liquid introduced into a pipeline shall, where possible, be not less than 61°C, to prevent the formation of explosive gas/air mixtures.

NOTES:

1 The operating authority should consider the risks of introducing lower flash-point hydrocarbon liquid and take appropriate measures.

2 Physical separation using a batching pig is recommended. This can be improved using a slug of inert liquid or high flash-point hydrocarbon in front of the pig to improve separation.

3 The use of an immiscible fluid like water may introduce contamination risks, and the risk of corrosion to the pipe invert where trace quantities may exist for long periods after the initial filling.

NOTE – When the pipeline has not been designed to allow pigging, alternative procedures shall be developed and approved.

Filling a high vapour pressure liquid (HVPL) pipeline

Where the HVPL consists of a single component hydrocarbon, the pipeline may be filled in the gas phase, upon which the pipeline shall be pressurized to above the dewpoint of the HVPL and the pipeline confirmed as fully liquid. Procedures for the pressurization and recondensing of the gas phase HVPL shall be approved. Where the HVPL is a mixture of hydrocarbon components, the pipeline should be filled first with water or a suitable low vapor pressure hydrocarbon liquid, and then that liquid displaced by the liquid phase HVPL. Suitable spheres or pigs should separate the two liquids. The pressure shall be maintained at, or above, the bubble point of the HVPL, to maintain it in its liquid phase.

NOTE: Where the HVPL consists of a mixture of hydrocarbon components other than ethane and the risk of contamination with inerts is considered low, the operating authority should complete a process simulation and prepare specific procedures to fill the pipeline in the gas phase. The operating authority needs to be aware of the effects of the variation of the composition of the re-condensed HVPL along the pipeline, the potential low temperature effects and of the difficulty in determining when the pipeline is in a total liquid state.

sumber: http://oanaalexandra.hubpages.com/hub/Commissioning-of-Submarine-Pipeline-Systems, diakses 3 Februari 2014

Oleh: blackturtle36 | Februari 3, 2014

How are pipelines constructed?

How are pipelines constructed?

Pipelines cannot be constructed overnight, and the entire construction process can take up to 18 months.

Natural gas pipelines are constructed in response to the evolving supply and demand dynamics of the natural gas market.  In order to construct an interstate pipeline, a company must receive authorization from the Federal Energy Regulatory Commission (FERC or Commission), which includes a determination that there is a need for the facility and a thorough review of the proposed pipeline route and the environmental impacts associated with the proposed facilities.

Before construction can begin, the company must obtain legal rights to the land along the proposed route, called a right-of-way, from landowners.

description for How are pipelines built?

Construction in Progress

A pipeline construction project looks much like a moving assembly line.  A large project typically is broken into manageable lengths called “spreads,” and utilizes highly specialized and qualified workgroups.  Each spread is composed of various crews, each with its own responsibilities. The tasks include:

Steps in the constructions process:

  1. Clearing, grading and trenching
  2. Stringing and welding pipe segments together
  3. Depositing the pipeline, backfilling and testing
  4. Restoration

As one crew completes its work, the next crew moves into position to complete its piece of the construction process.  Each spread may be 30 to 100 miles in length, with the front of the spread clearing the right-of-way and the back of the spread restoring the right-of-way.

sumber: http://www.ingaa.org/cms/65.aspx, diakses 3 Februari 2014

New Welding Technologies Provide Dramatic Advantages for Pipeline Welding

natural gas pipelineThe installation of gas pipe through the designated wetland areas of Mississippi and Alabama could prove challenging for any contractor, but the thick-walled pipe specified on the Gulfstream Project presented new welding challenges for contractor Sunland Construction Inc. Because the pipe is two times as thick as that typically used, Sunland relies on innovative welding techniques to decrease the number of weld passes necessary and most importantly, to assure the welds produced are consistent, x-ray quality.

Sunland Construction Inc., headquartered in Eunice, Louisiana, turned to The Lincoln Electric Company’s Autoweld® automatic orbital pipe welding system for the fill and cap passes and the STT® (Surface Tension Transfer®) process to lay the critical root pass. By implementing these new welding technologies, Sunland has been able to remove one electrode pass from the root pass process as well as eliminate all grinding from this step. With the Autoweld system, the company has reduced the time to put in the fill and cap passes.

“We have realized dramatic improvements since using the new Lincoln welding systems in both higher quality and time savings,” said Joe Ratcliff, Project Manager for Sunland Construction Inc. “Our welders are proud of the new equipment, it has made the welding portion of this job run smoothly.”

Gulfstream Project

The Gulfstream Project is a natural gas pipeline that originates near Pascagoula, Mississippi and crosses the Gulf of Mexico to Manatee County, Florida. Once onshore, the pipeline stretches across south and central Florida to Palm Beach County. This natural gas pipeline will serve Florida utilities and power generation facilities, generating 1.1 billion cubic feet per day of additional natural gas – enough to supply electricity for 4.5 million homes.

Sunland Construction Inc.’s portion of the pipeline includes installation of 6.1 miles of 36″ diameter pipe in Jackson County, Mississippi and 9 miles in Mobile County, Alabama.

A 27-year-old company with five divisions, Sunland won the Gulfstream job through a competitive bid process. More than 250 employees are being utilized on this project – taking a total of seven months to complete. Sunland expects its portion of the Gulfstream project to be wrapped up in early 2002.

According to Ratcliff, preparing for pipe installation on this job is no small feat. “Before we can even begin to weld, we must first clear the land, prepare a right of way, install piling in some areas, erect construction bridges and bring in additional soil where need. Because of the conditions of the wetland areas, all welding crews have to work on large, 4 ft. x 20-ft. timber mats. These mats, sometimes put down in a number of layers, provide a stable, dry work surface. Once work is complete in an area, Sunland Construction Inc. is also responsible for restoring the surrounding area to its original condition.

“Welding for this job is completed with three crews, one welding right after the other,” noted Ratcliff. “The first crew installs the root pass, the second crew immediately follows using stick welding to accomplish a hot filler pass, and then the Autoweld crew completes the welding process with fill and cap passes.”

Because of the extreme conditions on the site, the Autoweld process is performed inside of a welding “house” or modular unit that is lifted and moved every 40 ft. (from joint to joint) by a Caterpillar Challenger with a side boom.

extreme conditions at the gulfstream project site

The Pipe

Pipe for the on-land portion of the Gulfstream Project is provided by Berg Steel Pipe Corporation of Panama City, Florida and its parent company, Europipe GmbH of Germany. The X70 pipe ranges in wall thickness from 0.635 to 1.22. This thick-walled pipe was specified so the pipeline could handle the pressure range of the Gulfstream system. Pipe is coated with a Fusion Bond Epoxy (FBE) on both the interior and exterior, and a majority of the pipe is also concrete coated for buoyancy control.
Root Pass

Sunland Construction Inc. utilized the STT process because of the advantages it offered.

STT is a modified MIG process that uses high frequency inverter technology with advanced Waveform Control to produce high quality welds while also significantly reducing spatter and smoke. STT technology has the ability to control weld puddle heat independently of wire feed speed – this allows the welder more control over the puddle and provides the ability to adjust the heat input to achieve the desired root bead profile. The welder simply positions the arc on the forward portion of the weld puddle and follows it around the pipe in a vertical down fashion.

STT is a modified MIG process that uses high frequency inverter technologyWith the system, Sunland welders can achieve a uniform gap by using an internal, pneumatic clamp to line up and space the pipe for accurate welding.

For the Gulfstream Project in particular, STT is able to produce a quality weld and allows an increased amount of weld metal to be placed on the heavy wall pipe for improved resistance to cracking. With STT, Sunland only has to make one pass for the root bead as compared to two passes plus grinding time with stick.

“Since the root pass is the foundation for the rest of the weld, achieving a high quality, strong and uniform weld is very important to us,” said Ratcliff. “We are very pleased with the STT. It has allowed us to save time and is an easy system for our welders to learn. The STT process is very forgiving, meaning that it helps compensate for misalignments, if and when necessary.”

two STT machines on the Gulfstream job site are used in conjunction with Lincoln's .045 L-56™ SuperArc® wire and 100 percent CO2The two STT machines on the Gulfstream job site are used in conjunction with Lincoln’s .045 L-56™ SuperArc® wire and 100 percent CO2 shielding gas. As compared to blended gases, CO2 is able to provide better penetration and is less expensive.

“The STT is able to apply a root bead with great consistency over a wide variety of joint conditions” explained Ratcliff.

Hot Filler Pass

Once the root pass is complete, the next team of welders follows closely behind to weld in the hot filler pass. Due to the thickness of the pipe on this job, Sunland Construction Inc. elected to put a single downhill hot filler pass over the root with a downhill, low hydrogen stick process. “The added filler metal we deposited at this stage gives us additional backing to lay the first wire filler and means that we don’t have to make quite as many passes with the Autoweld system,” noted Ratcliff.

To do this interim step, Sunland is using Lincoln’s LH-D 80 rod with a conventional 300-amp Lincoln belt-driven welder.

Fill and Cap

For the Gulfstream Project, Sunland Construction Inc. decided to invest in an automated process to weld the fill and cap passes. Previously, Sunland has been completing the fill and cap passes with a 70+ stick electrode, welded vertical down and requiring numerous passes.

“We wanted an automatic method to increase efficiencies and decrease overall costs,” said Ratcliff. “It was also important for us to find a system that could provide a quality product but yet was easy to operate.

In its quest, the company contacted a number of manufacturers to research which system would work best in this application. “We narrowed down our choices and visited a couple of manufacturers to try out their systems, one of those being Lincoln Electric,” noted Ratcliff. “Our team traveled to Lincoln’s Cleveland headquarters where we had the opportunity to run our procedures on an actual Autoweld set-up. After we returned, we listed the pros and cons of every system and Lincoln’s Autoweld came out on top. A big factor in our decision was the amount of technical support that Lincoln could provide to us.”
autoweld systems were enclosed to allow work during all weather conditionsThe Autoweld system is enclosed in a house, so that welding can be done out of the elements. These houses are moved by sidebooms ( Challengers ) from one length of pipe to the next. Sunland uses six Caterpillar Challengers with PTO driven generators to produce the 100 amps at 460 volts needed to operate the Autoweld and accessories.

Lincoln’s Autoweld system uses a specially designed lightweight-welding head to travel around the circumference of the pipe. In addition, the unit utilizes an external crawler band placed on the pipe to one side of the field joint weld bevel. Two machines operating simultaneously complete the vertical up welding – one machine starts at the bottom with the other starts on the side. Once the machine that started on the side reaches the top, it then is positioned to start at the bottom to complete its side of the pipe. Using the vertical up process is a break from the traditional, vertical down welding typically utilized for pipe.

Each wall thickness of pipe requires different machine settings for each specific pass. These settings are charted and can easily be set from the machine. The Autoweld system uses a flux core .052″ wire and a shielding gas of 25 CO2/75 argon.

With Autoweld, Sunland Construction Inc. is achieving repetitiously consistent, x-ray quality welds. “Autoweld makes a very consistent, uniform, and precision-controlled metal deposit,” noted Ratcliff. “The weld has high tensile strength and good Charpy values in the weld and pipe heat zones. The machine is also very durable and dependable.”

Sunland’s Autoweld system is powered by an Invertec® V350-PRO, an extremely lightweight inverter that is able to handle multi-process applications. The hallmark of this power source is an extremely smooth arc due to the unit’s advanced inverter technology.

“We feel the V-350 is the state of art in welding equipment, it gives you the ability to maintain precise settings and arc performance,” claimed Ratcliff. “Even after long hours of use on our construction site, the machine was dependable.”

Quality Control

All welds once completed are visually inspected and then x-rayed with an internal crawler. All welds must meet API 1104 Section 9 requirements.

Service

STT and autoweld systemsSunland Construction Inc. has been extremely pleased with the service it receives from Lincoln. “The on site support provided by the Lincoln Electric Mobile team of Troy Gurkin and Steven Brown has been superb,” said Ratcliff. “We also enjoyed tremendous support from the Cleveland based Autoweld group including Eric Stewart, Autoweld technician, who was on site for much of the project. Lincoln has gone out of its way to help us implement our new processes and suggest new technologies when appropriate.”

Sunland has also taken advantage of Lincoln’s training programs on-site and in Cleveland. “Lincoln was challenged with taking welders at all different levels of expertise and work with them to learn to understand and operate the Autoweld system. It was a massive training effort that required quite a bit of Lincoln’s time. We appreciate all they have done to make this job run smoothly.”

Future

Sunland Construction Inc. is already planning on how the new STT and Autoweld machines can be used on future jobs to increase efficiencies.

sumber: http://www.lincolnelectric.com/en-us/support/application-stories/Pages/sunland-surface-tension-transfer-welding.aspx, diakses 3 Februari 2014

Oleh: blackturtle36 | Februari 3, 2014

Baltic pipeline in subsea tie-in phase

Baltic pipeline in subsea tie-in phase

Work has started on underwater tie ins of the second Nord Stream gas pipeline in the Baltic Sea.

During the two-week operation, two of the 1,224-km (760-mi) pipeline’s three sections offshore Finland will be joined inside a hyperbaric welding station.

As with the parallel Line 1, the three sections feature reduced pipe-wall thicknesses as the design pressure of the gas drops from 220 to 177.5 bar (3,191 to 2,574 psi) on its journey from Portovaya Bay, northern Russia to Lubmin on the German Baltic Sea coast. This design means there is no need for an interim compressor station, reducing the amount of steel required and allowing faster pipelay.

The hyperbaric tie-ins are being performed at two offshore locations where the design pressure changes from 220 to 200 bar (3,191 to 2,901 psi) and from 200 to 177.5 bar (2,901to 2,574 psi), respectively.

Connection of the central and southwestern sections will take place in June off the Swedish island of Gotland in a water depth of around 110 m (361 ft).

Welding operations will be set up by divers and remotely controlled from Technip’s DSV Skandi Arctic, using equipment from the pipeline repair system administered by Statoil on behalf of a pool of pipeline operators.

Three pipe-handling frames will be lowered from the vessel and positioned over the pipeline ends on the seabed. The frames will move the ends of the overlapping parallel pipeline segments to aline them for welding after they are cut to the correct length. Pipe ends will then be beveled and the pipes lifted and moved into place.

Welding should take a day. The weld will be inspected with ultrasound and, assuming an acceptable outcome, the welding equipment will be retrieved to the vessel while the pipe-handling frames lower the pipeline back on to the seabed.

All water will be removed from the completed pipeline during the summer followed by drying of the evacuated pipeline.

Nord Stream 2’s onshore and offshore sections will be connected early in the fall, and after testing, the line is scheduled to come onstream before end-2012.

sumber: http://www.offshore-mag.com/articles/2012/05/baltic-pipeline-in-subsea-tie-in-phase.html, diakses 3 Februari 2014

Oleh: blackturtle36 | Februari 3, 2014

Risk Assessment; Northern Gateway Pipeline

Risk Assessment; Northern Gateway Pipeline

The public arguments used by the proponents of the Gateway are that the pipeline will reduce Canada’s dependency on the market to the States. It will enable Canadian producers to ship 500 thousand b/d to China at a higher price than the Americans pay. And it will have tremendous economic value and minimal environmental impact. These arguments have three significant limitations. One is the conditions of the North American Free Trade Agreement (NAFTA). The second is the total amount of Canadian oil available now and in to the future. The third is the long term economic benefit and cost of the development and operation of the pipeline.

Firstly, Canada only produces enough oil to meet current its current obligations under the NAFTA (Chp. 6, Art. 605) of 2.1 million b/d to the States for the next 3 years.  A summary of Canada’s total oil production from all sources for 2011 was 2.9 million b/d.  1.6 million b/d was produced from the oil sands. Canadian domestic use is about 500 thousand b/d and growing as our economy grows. At the same time Canada’s conventional oil production (sources other than oil sands) is declining by about 10% to 15% per year. This means that at 2011 rates we have an export surplus for oil of about 300 thousand b/d.  Any projected surplus is based on the assumption that United States oil demands won’t increase and that Canadian supplies will.

Secondly, there is no credible evidence that the production in the oil sands will be able to be increased to make up for the energy short fall that is expected to continue to occur in conventional production. This means that there would be about 300 thousand b/d of oil available for export to China. So unless the Canadian government intends to rescind the NAFTA, the argument that Canada will cut off exports to the States and export 500 thousand b/d to China is simply not credible.

Thirdly, the construction of a pipeline benefits very few people over a very short period of time. On the other hand a pipeline, like any other mechanical device, will break down. It’s just a matter of when. So the risk of an oil spill is not only foreseeable it is inevitable. The pipeline will just make it easier, cheaper, and safer to transfer oil through Canada then have it freighted to the under used refineries in California. This looks like Canadian long-term risk with American long-term benefit. And China is just a convenient diversion.

Sumber: http://www.environmentalsociety.ca/main/blog-posts/risk-assessment-northern-gateway-pipeline/, diakses 3 Februari 2014

Oleh: blackturtle36 | Februari 3, 2014

How Line Pipe Is Manufactured

How Line Pipe Is Manufactured

Production of steel pipe is grouped into two general categories: WELDED and SEAMLESS.
There are many methods of producing steel pipe in current use. However, most of the pipe produced in the United States is made by either the Continuous Weld, the Electric Resistance Weld, the Double Submerged Arc Weld or the Seamless method.

CONTINUOUS WELD PIPE:

Continuous weld pipe is produced in sizes from NPS Va to NPS 4. Production begins with coiled skelp of the required width and thickness for the size and weight of pipe to be made. Successive coils of steel are welded end to end to form an endless ribbon of steel. The coiled steel is fed into a roll leveler and then into agas fired furnace where it is heated to the required temperature for forming and welding. The forming rolls at the exit end of the furnace shape the heated skelp into an oval. The edges of the skelp are then firmly pressed together by welding rolls to obtain a forged weld. The heat of the skelp, combined with the pressure exerted by the rolls form the weld. No metal is added in the operation. The final rolls on the mill reduces the diameter and wall thickness to bring the pipe to its finished dimensions.

Synchronized with the speed of the pipe as it emerges from the final rolls is a rotary saw which cuts the pipe to its desired length. The pipe is then cooled, descaled, straightened, inspected. tested hydrostatically, coated as required and end finished. Continuous weld pipe is commonly used for the conveyance of water. air. gas, steam; for sprinkling systems, water wells. fencing. and a multitude of structural applications. C.W. pipe is generally the lowest cost steel piping material available. It is available in the following specifications: ASTM A-120 (withdrawn 1988). A-53. A-501. A-589, A-618. and API5L.

Continuous weld pipe is normally produced in three weights:
Standard. Extra Heavy, and Double Extra Heavy NPS Va to NPS 4 Lighter weights than standard are available in certain sizes. Continuous weld pipe is available with square ends. beveled 30° for welding, threaded both ends, threaded and coupled and victaulic grooved for use with victaulic couplings. Surface finishes are available in Black (oiled). Galvanized. and Bare. CW. Pipe is also supplied with Inorganic coatings (adodic chromate, oxide and vitress enamels); Organic coatings (paints. varnishes. lacquers. rubber, and plastics such as x-tru coat and Scotchkote); Bituminous coatings (asphalt and coal tar).

Continuous Weld pipe is available in 21 foot uniform lengths. single random lengths from 16 foot to 22 foot and double random lengths from 38 foot to 42 foot. Continuous Weld pipe in sizes NPS 1V2 and smaller are normally put in standard bundles as indicated in the following chart.

CONTINUOUS WELD STEPS OF MANUFACTURE

1. Coiled strip is loaded onto feed table.
2. Strip is fed into roller leveler.
3. Ends of strip are sheared.
4. leading end of coil is flash welded to trailing end of previous coil.
5. Strip is formed into loop.
6. Coil is delivered into furnace.
7. Strip is heated in furnace to approximately 2450°F, strip edge is heated to 2600°F.
8. Forming rolls bend strip into an oval. At the welding stand the heat in the skelp and the pressure of the rollsforms the weld.
9. Pipe is stretch reduced where the desired 00 and wall thickness are obtained.
10. Flying cutoff saw cuts pipe into double lengths.
11. Final 00 sizing on sizing mill.
12. Pipe is cut to finished length, straightened and inspected.
13. Pipe is hydrostatically tested, end finished, stenciled, and coated as required.

ELECTRIC RESISTANCE WELD PIPE:

Electric Resistance Weld pipe is normally produced in sizes from 2% inch 00 NPS 2 thru 24 inch 00. (NPS 24) ERW is produced from individual sheets or continuously from rolls of skelp. There are two important differences. In the production of ERW pipe as versus CW pipe. ERW pipe is cold formed into a cylindrical shape rather than hot formed. An electric current rather than a flame is used to heat the edges of the strip for the fusion weld. Revolving copper discs serve as electrodes and raise the temperature to about 2600°F for effective welding. As in CW pipe, no extraneous metal is added; in fact, due to the extreme pressure of the rolls, steel is extruded on both the inside and outside of the pipe at the point of the weld. This is called flash and is removed by stationary cutters while still white hot.

As in CW production. ERW pipe is subject to numerous finishing operations. ERW pipe is primarily used as API Line pipe for the transmission of gas and oil. It is also used for the transmission of water. Under AWWA specifications. as piling and slurry pipe and in mechanical applications.
ERW pipe is available in the following most common specifications: ASTM A-53 Grade;A & B;A-135
A-252 Grade 1. 2, 3;API5L Grade A & B; and API5LX42 thru X-55.

ERW pipe is available in lengths from single random to 80 feet. ERW pipe is available with square ends or beveled for welding, threaded and coupled and victaulic grooved. Surface finish are available in black or bare, or with protective coatings, as described in C.W. section.

Major purchasers of ERW pipe are:

Utility Companies,Oil Companies,Steel Fabricators, Piling Contractors,Dredging Contractors,Water Well Contractors,Pipe Distributors, Pipe Line Companies, and Federal, State. and Local Governmental Agencies.

ELECTRIC RESISTANCE WELD STEPS OF MANUFACTURE

1. Coils of strip steel or skelp on feed ramp. From this position it is uncoiled, flattened, and the leading edge of the coil is sheared.
2. First forming section transforms strip into a round pipe section.
3. Fin pass section finishes rounding process and prepares edges of strip for welding .
4. The edges of the strip are heated to 2500°F by high frequency welder. The edges are squeezed together by pressure.
5. Weld is inspected electronically for some specifications.
5. Seam is normalized.
7. Weld is cooled by air and water.
8. Pipe is sized and straightened.
9. Pipe is cut to required length by flying cut-off saw.
10. Pipe is visually inspected.
11. Pipe is hydro-statically tested.
Final finishing includes inspection, end finishing, coated as required, and stenciled.

SEAMLESS PIPE

‘Seamless pipe is produced domestically in sizes NPS ‘Ie through NPS 26 00. Seamless pipe is produced without a seam or weld in the circumference. Seamless pipe is produced by a variety of methods. To put it in its most simple terms, seamless pipe is produced by piercing a solid billet of deoxidized and conditioned steel, which has been properly prepared and heated to the proper temperature. It is then processed through a series of mills where the pipe is finished to its prescribed dimensions. Seamless sizes over 14 inch 00 are usually rotary rolled from 14 inch seamless shells which expand the diameter and reduce the wall thickness to the approximate dimensions required. Small sizes of seamless pipe are generally obtained through the use of a stretch reduced mill. In this process the outside diameter and the wall thickness of the pipe is reduced through a series of rolls. Seamless pipe goes through various finishing operations including straightening, inspection, testing, and end finishing. Seamless pipe is widely used in construction, oil refining, chemical and petro-chemical industries.

Seamless pipe is available In the following specifications: ASTM A-53 Grades A & B; A-106 Grades A.B, and C; A-252 Grades 1,2,and 3; A-333 Grades 1 through 9; A-335 Grades P-1 through P-22; A-501, A-523, A-589, API5L Grades A & B, and API5L X-42 through X-65.

It is common practice to dual stencil seamless pipe with API5L and ASTM A-53 monograms. Seamless pipe is available in single random and double random lengths. It is not normally supplied in uniform lengths. End finishes for A-53 include plain ends, either beveled or square cut, grooved for victaulic couplings and threaded and coupled. Grades other than A-53 are normally supplied in plain end only, either square cut or beveled. In sizes 6% and over, in thicknesses 3/4 inch and over, a “two-step” bevel is available.

Seamless pipe is available in black, bare, galvanized, or with protective coatings as described in C.W. section. The following are major purchasers of seamless pipe: Pipe Distributors, Plumbing & Heating Supply Houses, Mechanical Contractors, Oil and Gas Companies, Chemical Companies, Power Generation Equipment Manufacturers, Railroads, Shipbuilders, Utility Companies, Governmental Agencies, Pipe Fabricators and Water Well Contractors.

DOUBLE SUBMERGED ARC WELD PIPE

Double submerged arc welded pipe (DSAW) derives its name from the welding process wherein the welding arc is submerged in flux while the welding takes place. Both inside and outside welds are required and are usually accomplished in separate processes, hence the word “double.” These separate welds consume a portion of the other resulting in a single high quality weld nugget.br/
DSAW pipe is produced in sizes from 18″ through 72″ 00 and wall thicknesses from .250″ through 1.5″.

Two different processes are used to manufacture DSAW pipe; the pyramid rolls method, and the U-O-E method. The difference in the processes is found only in the method of forming the cylinder. In the pyramid rolls process the cylinder is formed between 3 rolls arranged in a pyramidal fashion. As the name implies; the U-O-E method uses a “U” press, and “0” press for forming. Other parts of the process such as finishing and inspection are similar. Both processes use flat steel plate as the raw material.

DSAW pipe mayor may not be cold expanded. Cold expansion is a process where the pipe is expanded (up to 1_5%) to obtain its final 00 dimension. In the process, a gain of yield strength results. Expansion is most often utilized in a U-O-E mill due to the need to recover the yield strength lost during forming in the “0 press, DSAW pipe is available in the following grades:
ASTM A134, A139, A252, A671, A672, A690, A691, CSA (Canadian) – Z245.1 and custom specifications. API 2B, 5LB, 5LX-42 thru 5LX-80

DSAW pipe is normally produced in double random lengths with square ends or beveled for welding. It is usually furnished bare but varnish is also offered. A wide range of external coatings and internal linings are available with DSAW pipe. These include fushion bond epoxy (FBE) coatings and thin film epoxy linings. DSAW pipe is used in high pressure gas and oil transmission lines (both onshore and offshore), structural members and pipe piles. Major purchasers include liquid and gas transmission companies, hammer companies, construction contractors, platform fabricators, government agencies and pipe distributors.

SPIRAL WELD PIPE

Spiral Weld Pipe, as the name implies, is a steel pipe which has a seam running its entire length in a spiral form. In the past, due to the method of manufacture, Spiral Welded pipe was relegated to low pressure and structural applications. With the development of the Submerged Arc Welding process, the production of large hot rolled coils of sufficient width and the development of dependable non-destructive testing methods, it is now possible to produce Spiral Weld pipe for high pressure service.

Present Spiral Weld mills consist of a de-coiling device (in the case of strip base material) or a plate preparation table (where the base material is in plate form) a strip connecting welder, straightening rollers, edge preparation tools (shearing and trimming), prebending devices, a three roller bending and cage forming system, an internal welder, an external welder (both Submerged Arc), ultrasonic testing apparatus and cutting devices. The material passes through all these production stages continuously. The angle between the flat strip being I fed into the machine and the finished pipe leaving the machine controls the pipe diameter in ratio to strip width and the angle of the weld in the pipe.

Because of the method of manufacture, a wide variety of diameters can be produced. The diameter tolerance is small, particularly with regard to ovality; and the pipe, due to its axial symmetry, has an inherent straightness. The length range is infinite and is controlled only by the economics of transportation. Spiral Weld Pipe is used for dredging, slurry, water and other pipelines, as well as piling and structural applications. Spiral Weld Pipe is produced in accordance with the dimensional and tolerance requirements of various ASTM, AWWA, and API Specifications.

Sumber: http://midstate-steel.com/how-pipe-is-manufactured.html, diakses 3 Februari 2014

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