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Welding

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Welding is the process of joining separate metals together using extreme heat. Welding can be used for a number of different purposes. For example, repair welds are minor welds that are applied to structures to repair areas of minor surface damage. Weld overlay, on the other hand, is a process that is used to add an outer layer to a piece of equipment.

There are multiple different welding processes. Some of the more common types of welding are shielded metal arc welding, CO2 welding, Metal Inert Gas (MIG) welding, Submerged arc welding, and Plasma Transferred Arc (PTA) welding.

After performing any weld. it is important to perform a post weld heat treatment (PWHT) on the weld area to reduce residual stresses. If this is not done, then the weld is more likely to experience brittle fracture. PWHT is also able to reduce the chances of hydrogen induced cracking (HIC) in the weld as well.

Hot Work

Hot work refers to any work involving electric or gas welding, cutting, brazing, or similar flame or spark-producing operations. In many oil and gas or chemical processing enviroments, hot work has the potential to ignite a combustible material and cause significant process safety incidents. Extreme caution must be used whenever planning and performing any hot work.

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Articles about Welding
March/April 2021 Inspectioneering Journal

This article discusses the benefits of an established heat treating process with regards to mechanical integrity, as well as certain quality control measures and the importance of a heat treatment plan.

Authors: Ben Osborne
January/February 2021 Inspectioneering Journal

Thermal fatigue, a specific form of fatigue driven by varying metal temperature gradients and ensuing differential thermal expansion, is generally most effectively mitigated by reducing the severity of metal temperature gradients.

November/December 2020 Inspectioneering Journal

The author estimates that, if the composite repair approach is implemented properly in place of welding repairs, approximately 70-80% of hot work at operating sites could be eliminated.

Authors: Ashfaq Anwer
November/December 2020 Inspectioneering Journal

Heat treatment has been used by mankind for centuries. This article details reasons to heat treat, the types of heat treating available, methods of heat treating to achieve specific material properties, and the role of MI in heat treating.

Authors: Ben Osborne
January/February 2020 Inspectioneering Journal

There are many sources and occurrences of metal fatigue in the chemical and refining industries. They range from low-cycle thermal stresses in an FCCU, to the relentless pressure cycling of a PSA, to the ultra-high cycles of a rotating pump.

Authors: Greg Garic
Partner Content

LOTIS utilizes laser profilometry to conduct internal steam reformer tube inspections. The data captured by LOTIS is exceptionally powerful when combined with our LifeQuest™ remaining life assessment capabilities, providing an integrated...

Blog

We’re excited to announce a new section of our website that is dedicated to equipping inspectors with greater knowledge and proficiency across various subject matter areas.

November/December 2019 Inspectioneering Journal

This article helps shine light on some common industry problems that can occur by having inferior UT procedures and practices, while providing several lessons learned through a case study that resulted in nearly $1 million in turnaround repairs.

July/August 2019 Inspectioneering Journal

This is the second of a two-part column on “Creep.” This second part discusses the approach to creep assessment in plant equipment.

Authors: Greg Garic
May/June 2019 Inspectioneering Journal

This is the first of a two-part column on “Creep”. It presents an engineering overview of the phenomena, answers the question: “What is Creep?”, and provides readers with foundational knowledge for evaluating and managing remaining...

Authors: Greg Garic
Blog

Over the last six months, Inspectioneering has released a plethora of interesting and educational content that has been read more than 150,000 times online. In case you missed it, here's a recap.

Partner Content

Auto-refrigeration can impose low temperatures onto process vessels and piping causing them to be at risk of brittle fracture, the sudden break-before leak phenomena that can result in catastrophic rupture of the equipment.

March/April 2019 Inspectioneering Journal

The quality of the thousands of factory and field welds present in pressure part modules is critical for assuring reliable operation over the life of a plant. Companies should be doing more than paying lip service to quality. Don't just tick a box.

January/February 2019 Inspectioneering Journal

Welding imperfections vary in impact from being acceptable to requiring repair. It is important to ensure the quality of welds using NDT and to ensure the strength of the entire piping system with hydrotesting.

Authors: Qasem Fandem
January/February 2018 Inspectioneering Journal

Given the concern throughout industry regarding the potential for brittle fracture failures, PWHT guidance to address potential issues arising from the recent changes in PWHT code requirements for carbon steel is examined in this article, and...

May/June 2017 Inspectioneering Journal

The "simple" process of PWHT is more complicated than it may appear at first glance. Knowledge of the procedures, attention to details, and actual experience are indispensable in preventing failures caused by improper PWHT.

July/August 2016 Inspectioneering Journal

The structural integrity of components is controlled by material properties, the presence of flaws, and levels of applied stress. Several factors such as temperature, type of loading, toughness, corrosion resistance, micro-structural stability, cost...

Partner Content

FFS assessment techniques are applicable to a wide range of damage types: LTA's, cracks, creep damage, dents, and more. These are very powerful analytical tools that often allow operators to not only keep the plant running, but to keep it running...

July/August 2016 Inspectioneering Journal

This article summarizes a recent finite element analysis (FEA)-based study that employs creep simulation techniques to investigate the elevated temperature response of piping with peaked longitudinal weld seams.

March/April 2015 Inspectioneering Journal

Weld inspection using lasers is not new, but doing it 75 meters inside a pipe or streaming inspection data wirelessly is new. As laser technology has improved, more industries such as oil & gas are beginning to require laser inspection as part of...

January/February 2015 Inspectioneering Journal

Are you still hitting the welded joints of pressure vessels with a hammer during hydrostatic testing? If yes, then you’re due for a refresher on the pressure testing requirements of ASME Section VIII Division 1 since this requirement was for...

Blog

One of the more insidious problems within the industry is the issue of atomic hydrogen dissolving into steel equipment. This can happen to some steel components under certain circumstances and can cause weld failure, or what is known as “hydrogen...

Authors: Nick Schmoyer
September/October 2014 Inspectioneering Journal

A small leak from top tubesheet-to-tube welds prompted further inspection of the 1¼Cr- ½Mo Ammonia Converter Boiler Feed Water (BFW) Exchanger during a planned shutdown. Further cracks were identified in the top channel to tubesheet butt weld that...

Partner Content

Equity Engineering Practices® (EEPs) are a collection of detailed & customizable Best Practices integrated with a customizable management system. EEPs include: 650+ branded and customizable Best Practice Documents, 225+ Pre-Engineered &...

May/June 2014 Inspectioneering Journal

In November 2013, ASME released its updated PCC-1 guidelines for pressure boundary bolted flange joint assemblies. Contained within the document is Appendix A, which represents a major change from the previous 2010 release and is considered to be...

Authors: Neil Ferguson
January/February 2014 Inspectioneering Journal

This is the second of two articles published in Inspectioneering Journal discussing the value of hydrogen bake-outs. Our first article was published in the May/June 2013 issue and received a great response from the Inspectioneering community. In...

January/February 2014 Inspectioneering Journal

If necessity is the mother of invention, then the American Society of Mechanical Engineers (ASME), the Occupational Safety and Health Administration (OSHA), and the Environmental Protection Agency (EPA) are the parents of guidelines, standards,...

Authors: Neil Ferguson
January/February 2013 Inspectioneering Journal

In this article you will find the failure investigations of six 0.094 inch thick carbon steel vessels. These vessels were in service in natural gas well facilities; some functioned as dryers and were subjected to cyclic loads. Metallographic tests,...

Authors: Ana Benz
September/October 2010 Inspectioneering Journal

For years the WRC has provided the documented technical basis for many decisions made regarding design, repair, remaining life estimation, and fitness for service of pressure equipment in our industries. Many codes and industry recommended practices...

Partner Content

TEAM’s integrated touch point corrosion program manages all aspects of the integrity process from screening for damage to permanent repair assuring integrity – every time. TEAM’s unique turn-key approach to touch point corrosion integrity...

January/February 2008 Inspectioneering Journal

Most common radiographic practices for circumferential weld testing are single wall and double wall techniques with certain variations in technique details. Different Codes deal with the number of exposures required and applicability of the...

September/October 2007 Inspectioneering Journal

The Inspectioneering Journal Discussion Forum is a great storehouse of knowledge and experience for people involved in fixed equipment reliability. A few samples of discussions follow, to motivate you to participate.

Authors: Greg Alvarado
March/April 2007 Inspectioneering Journal

In the welded condition many stainless steels are susceptible to rapid intergranular corrosion or stress corrosion cracking. This is because the heat from welding sensitizes the base metal heat affected zone (HAZ) and the weld.

Authors: John Reynolds
March/April 2007 Inspectioneering Journal

A myriad of issues need to be considered before welding to or repairing weld overlayed or clad equipment. (By clad we mean roll-bonded or explosion bonded, i.e. basically 100% metallurgically bonded, and not a loose or seam-welded liner, e.g., not...

Authors: John Reynolds
March/April 2007 Inspectioneering Journal

When we talk about welding QA/QC we typically focus on the technical requirements and what QA/QC is needed to assure that the technical requirements are met. Examples include the preheat, interpass, and PWHT temperatures and how to assure that the...

Authors: John Reynolds
Partner Content

How is reliability affecting your bottom line? Download our Economics of Reliability report, where Pinnacle analysts take data from the oil refining industry and dive into how that key sector is being affected by reliability today.

May/June 2006 Inspectioneering Journal

As noted in the discussion on delayed cracking, when the steel contains hydrogen as a result of service exposure (or corrosion, or high temperature - high pressure hydrogen processing) then a hydrogen bake out may be needed to avoid cracking...

Authors: John Reynolds
January/February 2006 Inspectioneering Journal

After a pressure equipment or piping failure, it’s not uncommon to find out during the failure analysis part of the investigation that the failure initiated at a welding flaw of some sort.

Authors: John Reynolds
January/February 2006 Inspectioneering Journal

Among other things, a welding QA/QC program needs to ensure that only qualified welders, utilizing qualified procedures are allowed to weld on any pressurized equipment, including storage tanks and piping.

Authors: John Reynolds
July/August 2005 Inspectioneering Journal

This bulletin is part of a series of WRC Bulletins that contain the technical background and other information to evaluate damage mechanisms in various industries to facilitate the use of API 579. These bulletins, shown below, will be updated based...

May/June 2005 Inspectioneering Journal

Current BSI and ASME codes for the construction of pressure vessels, boilers and piping specify that post-weld heat treatment is required if the thickness of the components being welded exceeds a specified value. This value depends on the type of...

Partner Content

Traditional, paper-based inspection processes can prevent plants from being as effective as they can be. By digitalizing your mechanical integrity process and data with MISTRAS Digital®, plants have realized up to 75% gains in IDMS data entry and...

January/February 2004 Inspectioneering Journal

Repair welds can be another undetected and insidious "fabrication defect" that eventually results in equipment failure. Any experienced metallurgist that has completed numerous failure analyses over the years will tell you that periodically they see...

Authors: John Reynolds
January/February 2004 Inspectioneering Journal

When we specify that some equipment (vessels, flanges, fittings, etc.) be overlaid with a corrosion resistant alloy, we need to pay attention to making sure that the chemistry of the top layer of alloy welding, that will be exposed directly to...

January/February 2004 Inspectioneering Journal

DMW cracking is another fabrication issue that can and does result in equipment failure. It usually occurs at the weld juncture where carbon steel or low alloy steels are welded to austenitic (300 series) stainless steels in high temperature...

January/February 2004 Inspectioneering Journal

Cracks along the toe of a weld are not uncommon during fabrication, and can occur for a wide variety of reasons involving the metallurgy and process control of the the same issues covered above on repair welds can apply to repair welds on...

Authors: John Reynolds
January/February 2004 Inspectioneering Journal

Inadequate PWHT is one of our pressure equipment nemeses. We normally specify PWHT for a variety of pressure equipment integrity reasons including when we need to lower residual stresses, increase resistance to cracking or soften weld hardness. All...

Authors: John Reynolds
Partner Content

Antea delivers highly flexible risk-based asset integrity software with 3D Digital Twin integration to optimize maintenance, reduce risk, and improve mechanical integrity for oil and gas, power generation, and chemical plants and facilities. Whether...

May/June 2003 Inspectioneering Journal

A new recommended practice from the API is in the final stages of preparation before publications. It is API RP 577 on Welding Inspection and Metallurgy.

Authors: John Reynolds
November/December 2000 Inspectioneering Journal

Part 4 of this article continues to outline the 101 essential elements that need to be in place, and functioning well, to effectively and efficiently, preserve and protect the reliability and integrity of pressure equipment (vessels, exchangers,...

Authors: John Reynolds
September/October 1999 Inspectioneering Journal

This paper describes the use of a UT fixture for detection of stress corrosion cracking in ferrous heat exchanger tube-to-tubesheet welds and external tube corrosion or pitting near the tubesheets including crevice OD corrosion.

Authors: Reggie Cross
July/August 1998 Inspectioneering Journal

Visual inspection is the most common nondestructive testing method. For critical applications, machine vision technology provides advantages over visual inspection.

July/August 1998 Inspectioneering Journal

The debate about advantages and drawbacks of the application of the TOFD (time of flight diffraction) approach for ultrasonic weld inspection should not forget the original reasons for its introduction in the 1960s. The major advantage at that time...

Authors: H. Wuestenberg
May/June 1997 Inspectioneering Journal

Case 1: Fuel Gas to Boilers in boiler house: in 1992 two flanges were installed for installation of knock blinds. No degassing was completed. Both welds were radiographed and noted as acceptable. Case 2: Alky Unit Flare Header: No degassing...

November/December 1996 Inspectioneering Journal

The basic approach to the inspection and repair procedure for welding has barely altered for three decades. The normal practice has continued to be to inspect a weld only after the welding programme is complete. Thus by the time a defect is...

Authors: Shaun W. Lawson
May/June 1996 Inspectioneering Journal

This final issue on gusset problems will discuss why gussets are "stiffeners" rather than "strengtheners." The effective load bearing capacity of a member of given strength is based upon how large a cross-sectional area is carrying the load....

Authors: Del Underwood
January/February 1996 Inspectioneering Journal

Last issue, in keeping with the evaluation that "gussets are stiffeners, not strengtheners," we discussed welding around the ends of the gusset plate instead of just along the sides in order to reduce the stress concentration. A further improvement...

September/October 1995 Inspectioneering Journal

A key to any piping evaluation program is to understand where problems can occur. Vibrating piping can propagate a crack relatively quickly. Have you ever installed gussets to stabilize a vibrating pipe situation only to find, shortly thereafter,...

Authors: Del Underwood
May/June 1995 Inspectioneering Journal

For reason of economy, the hot reheat pipework in many US power plants is fabricated from seam-welded low chrome-moly carbon steel spools. Unlike girth butt welds, where the critical weldment microstructures can off-load stress to the stronger...

Authors: Bob Browne
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