Welding

By 803056

Date 08-19-2016 12:50

No idea of what you are asking.

Al

By welderbrent (*****)

Date 08-19-2016 13:12

Again Richard,

Details, details, details.

Some codes and/or WPS's may restrict the amount of time for completing all layers/passes of a multi-pass weld. Some do not. It can be in the code or job specs or WPS which often means it was written into the PQR first.

Some welds must have a certain amount of thickness before welding can stop and restart at a later date.

Details man, details.

He Is In Control, Have a Great Day, Brent

By Richard Burthon Date 08-20-2016 00:30

AI and Welderbrent,
I use API 1104 std for pipeline.
one of esential variable for API 1104 is time between root to hotpass (second layer). we can stop welding after 50% of the thickness but shall continue at the same day, isn't it..?
The PQR was made qualification in one day completed welding, that's why I asked, Can welding stop after 50% thickness and continue the next day but the PQR is qualified only in one day welding complete

By TRowe

Date 08-21-2016 02:52

Richard,

API Standard 1104, 20th Edition, 5.3 Procedure Specification states the following under 5.3.2.10 - Time between Passes:

The maximum time between the completion of the root bead and the start of the second bead, as well as the maximum time between the completion of the second bead and the start of other beads, shall be designated.

This must be on the Procedure Specification and followed when performing the Procedure Qualification, as well as during production welding.

The time between passes becomes an essential variable (5.4 Essential Variables) when "An increase in the maximum time between completion of the root bead and the start of the second bead constitutes an essential variable." (API 1104 5.4.2.8)

Check the Procedure Specification. If the time between passes is within the requirements of the Procedure Specification, all is good.

Todd

By 803056

Date 08-21-2016 14:26

Richard;

I believe the concern is the possibility the interpass temperature can possibly drop below the minimum preheat temperature it there is too much time between weld beads. Considering the thickness of pipe is relatively thin, there is the tendency to loose heat rather quickly. One means of ensuring the interpass temperature is maintained is to limit the "cooling" time between weld beads.

Excessive cooling rates increase the possibility of hydrogen assisted cracking and because the joints are "highly" restrained, due to the mass of the pipe, susceptible to cracking the root bead or cracking partially completed welds when the welds cool and contract.

Best regards - Al

By ali hussain Date 08-28-2016 15:32

Dear All,
I want to inquire about the vickers hardness values for procedure qualification,while material is a537 cl.2 thickness 45mm,welding with smaw process using E7018G electrode in 2G position.during welding our amp range 126-143 voltage 24-26 and heat input is 1.352-1.438 kj/mm.travel speed 140-153 mm/min.what should be the hardness values are acceptable in weld metal ,haz,and base metal and on which standard basis.