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> Prep or no prep?
ScratchStart
post May 28 2020, 12:38 PM
Joined: 28-May 20



Hi everyone, I'm new to this forum. I was hoping to find somewhere i could ask a question and get an experienced answer.

I'm welding 3mm plate that needs x-ray. I'm using mig. Do I run a prep or can I get away without? Advice will be much appreciated.
CChive68
post May 28 2020, 11:19 PM
Joined: 7-Apr 20



3mm plate butts that need radiographed? What is the extent of NDE required? Is it a pressure retaining part and to which standard? AWS ?
Further to your question. If you need to factor in NDE to a standard, I'm assuming that you've run a PQR and have developed a WPS to cover this weld? Are the welds single or double sided?
ScratchStart
post May 30 2020, 12:19 AM
Joined: 28-May 20



I'm in structural working to exe class 3 which requires 20% ndt. We have wpqr and wps for double sided weld on heavier gauge that will cover 3mm, but I was hoping to weld 3mm in one run, single sided, and if successful we can develop a new wpqr and wps for the actual job.
Technic Al
post May 30 2020, 09:56 AM
Joined: 14-Oct 03



Double sided would be more consistent....no prep needed but back grind....and it will help rectify any distortion.
ScratchStart
post May 30 2020, 05:22 PM
Joined: 28-May 20



Thanks Al,... noted. It makes sense to use the wps we already have in place rather than develop a new one, and it would make doubly sure it would pass radiography. One day I do hope to be able to make that pass in one! biggrin.gif
Technic Al
post May 31 2020, 04:10 PM
Joined: 14-Oct 03



Could you use a copper backing bar?
CChive68
post Jun 2 2020, 08:57 PM
Joined: 7-Apr 20



Good call by Technic Al but maybe not copper,depending on standard/acceptance criteria, if it's getting bombed. Double sided WPS does not cover for single sided as far as I am aware and I've never seen a "punch through", single sided weld, done on this thickness, that has to be bombed. Also,doing it double sided would help with distortion. Try to mechanise where possible to minimise the amount of stop/starts, as this will also help with distortion greatly.Which standard are you carrying out RT to as a matter of interest?
CChive68
post Jun 2 2020, 09:10 PM
Joined: 7-Apr 20



So ISO5817 class B applies. Not just to NDE but VT too........
ScratchStart
post Jun 6 2020, 03:59 PM
Joined: 28-May 20



Yes, ISO5817 CLASS B. It's a circumferential butt weld 1.3m in diameter and sat on rotators, so should be pretty straight forward. On a similar set up but with 6mm+ we can use UT, but because it's 3mm RT is required.

The wps I'm using states single bev, double sided weld, with a back grind and back weld. Which is fine for thicker material, but for 3mm I'm hoping to drop the bevel. Is this acceptable?
CChive68
post Jun 9 2020, 07:42 PM
Joined: 7-Apr 20



PQR to EN-ISO15614? WPS to EN9606?
As far as I can see, included angle is not any kind of variable. Watch clause 8.4.3 (h) in 15614 re multi/single run though. If your WPS is qualified on a multi run butt, you cannot use it for single run butts. This includes single run from two sides as well.I am not a welding engineer, so take qualified advice on this.
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