Press

Weld Purging Post Weld Heat Treated (PWHT) Pipework

Posted by Michaela Reay

13-Feb-2019

huntingdonfusion.com


Welding processes can weaken metals by imparting residual stresses into a material, leading to a reduction in corrosion resistance properties. Post Weld Heat Treatment (PWHT) is regularly used to retain the strength of a metal when welding certain materials including high strength stainless steel and chromium-molybdenum (chromoly) steel such as P91.

Temperatures during PWHT might reach as high as 760ºC (1,400ºF) for many hours, during which time the insides of the pipes need continuous purging using Pipe Weld Purging Products. Many purging materials cannot withstand these temperatures, nor resist damage during the time at temperature.

HotPurge® Pipe Purging Systems have been designed and developed by Huntingdon Fusion Techniques HFT® for Heat-Treated Chrome and High Strength Stainless Steel Pipe Joints. 

Ron Sewell, Chairman for HFT® said: “To ensure welds are free from oxidation which could otherwise lead to joint imperfections, they must be welded in an environment free from oxygen that has to be maintained during the lengthy high temperature post weld heat treatment process.”

“It is not practical or cost effective to fill whole pipe lengths with Inert gas and restricting the weld purging zone has proven most effective. Argweld® HotPurge® Systems allow the purge to be safely continued for up to 24 hours whilst pre-heating, welding and post weld heat-treating with the purge system remaining in place.” 

The Argweld® Tube and Pipe Purging Systems are positioned inside the pipe with one dam each side of the joint and inflated with an inert gas supply. Once a System is fully inflated and sealed in a pipe, the inert gas displaces the oxygen from within the weld purging zone ready for pre-heating and welding. Each HotPurge® System is manufactured as standard with a Weld Purge Monitor® connection for viewing the oxygen level throughout the whole heating and welding processes.

Each HotPurge® System includes PurgeGate®, a revolutionary device to prevent over inflation of, and damage to the inflatable dams. No matter how high the user increases the pressure, in order to deliver more gas flow, PurgeGate® prevents pressure rise in the inflatable dams but allows an increased inert gas flow, to achieve a lower oxygen level and/or faster cooling of the weld zone. 

In addition, each HotPurge® System incorporates an innovative central band for easy positioning inside the pipe. This band, known as RootGlo®, will illuminate inside the dark pipe, for up to 20 hours, with only 10 minutes previous exposure to daylight.

HotPurge® Systems are manufactured to suit pipe diameters from 6 to 88” (150 to 2,235 mm) and both inflatable dams have pull handles securely sewn with high temperature resistant Kevlar thread that will withstand a pulling force of 1,000 lb.

These HotPurge® Inflatable Pipe Purging Systems can be used repeatedly for weld purging and will keep the oxygen levels below 100 parts per million (ppm) throughout the welding cycle, ensuring oxidation and coke free welds, without the metallurgical imperfections caused by exposure to too much oxygen.



New service from OilVoice
Trip Shepherd is for companies who need to track their staff in areas of risk.
It's free to use, so we invite you to try it.

Visit source site

huntingdonfusion.com

weld purgingpwht pipeworkhotpurgehuntingdon fusion

More items from michaelareay


Heavy-Duty Pipe Blocking with Steel Plugs

Heavy-duty pipe blocking and stopping is easy with the Steel Plugs Range from Pipestoppers®.  Pipestoppers®, a division of Huntingdon Fusion Techniques HFT®, manufacture Steel Plugs, which have been the favoured heavy-duty plug for applications such as leak testing, pipe stopping and blocking for ...

Michaela Reay


Posted 12 days agoPress > pipe stoppingpipe pluggingsteel plugs +2

Precise Tungsten Electrodes Tips with the TEG-1000

Correctly preparing each Tungsten Electrode for welding is crucial. It is one of the most important variables in TIG / GTA welding and each Tungsten Electrode must be ground properly to improve arc starting, stability and subsequently weld quality. Manufactured with a diamond wheel, the TEG-1000 T ...

Michaela Reay


Posted 19 days agoPress > teg-1000tungsten electrodestungsten electrode grinder +1

Weld Purging CMV Steels

CMV Steels (chromium / molybdenum / vanadium) are widely used for their high temperature creep properties especially in the steam turbine industries. Both pre and post weld heat treatment is necessary to achieve the optimum mechanical strength, but temperatures up to 300ºC (572ºF) must be maintain ...

Michaela Reay


Posted 24 days agoPress > hotpurgepipe purgingwelding cmv steels +2

Low Cost Weld Purge Dams

Weld Purging short pipe pieces and dome-end welds where tandem Inflatable Tube and Pipe Purging Systems are unsuitable, Huntingdon Fusion Techniques HFT® manufactures Weld Purge Dams. Ron Sewell, Chairman for HFT® said: “When welding tubes and pipes, the most cost- effective solution is to restric ...

Michaela Reay


Posted 1 month agoPress > pipe stoppingpipestoppershuntingdon fusion +1

High Temperature Weld Backing Tape®

Supporting the liquid weld root with a high temperature Backing Tape will ensure minimal oxidation and will require much less post-weld cleaning. Argweld® glass fibre Weld Backing Tape® from Huntingdon Fusion Techniques HFT® supports weld roots and eliminates the creation of slag, whilst removing co ...

Michaela Reay


Posted 1 month agoPress > backing tapeweld backing tapeback purge +1
All posts from michaelareay