Seam welding of sills?

andymc · 3rd October 2018, 14:44

I'm interested in getting some feedback from those in the know about welding. I had to replace the entire length of both sills on one of my cars after I'd left it standing for just over a year (other than starting it & taking it up and down the lane every few weeks). You live & learn ... Anyway, I took it for MOT last week and it was failed because the tester said it had to be seam-welded along the full length of the sill, as opposed to being spot-welded and then filled. When I took it back to the garage, they expressed surprise at this and said that seam-welding wouldn't even have been done in the factory, let alone for repair work. They also said that with seam-welding, due to the expansion and contraction of the metal as it is heated and cooled, there was a risk of creating a "twist" in the body of the car unless care was taken to avoid this by doing the job in stages.

They aren't refusing to take on the job, but I'm obviously not keen to pay for unnecessary work to be done either. I'm not knowledgeable enough about this to have an informed opinion, so I'd welcome input from those who know what they're talking about.

NB I'm in NI, which means the MOT stations are government-run and never do any repair work - their sole job is to do the testing. There's no chance whatsoever that the MOT tester is trying to generate work for himself.

RoverP480 · 3rd October 2018, 15:23

The factory would be spot welded if that has been done for the repair I cannot see the tester would fault it. Extract from NI test criteria.
Suitable materials of appropriate gauge or thickness should be used for repairs so that:
• Any plating or welding extends to a sound part of a load bearing component, and
• The repair must be virtually as strong as the original structure.
So only a continuous seam weld is acceptable for patch repairs (even if the patch extends beyond the prescribed area), although spot welded joints are acceptable where they originally existed (provided the original defective panel flange has been removed).
Stitch or plug welding is acceptable as an alternative to spot welding in these cases.
https://www.infrastructure-ni.gov.uk...ion-dvt938.pdf
I don't understand the " then filled" bit in your post

cbr1100xx · 3rd October 2018, 17:22

As I understand it , if you replace the whole sill panel then spot welds will do as they were used originally.
If its a repair patch then it has to be seam welded to make a continuous join .
Stan

marinabrian · 3rd October 2018, 17:47

A patch must be seam welded around the periphery area where it adjoins the original panel, however the part that abuts the adjacent panel where spot welds were employed originally may be plug welded or spot welded.

This has always been the case, however a continuous weld may consist of a series of stitch welds, as long as they form an unbroken seam.

This is important, as panel heat distortion is normally avoided by this type of repair.

Brian

philm · 3rd October 2018, 17:51

From the welding for MOT,S i have done in the past the top section of the sill where it joins to the original bodywork needs to be seam welded the lower part of the sill can be stitched or spot welded every couple of inches as manufactured but they are always changing the regs.

philm · 3rd October 2018, 17:52

Beat me to it Brian

andymc · 4th October 2018, 11:35

Many thanks folks, I'll pass on those responses.

Organiser · 4th October 2018, 15:52

MOT Standard Welding.

Someone once phoned me up must be 25 odd years ago and asked me if we did mot standard welding, I told him that we did not, when he expressed suprise at that being a bodyshop, I told him we didn't do welding that badly!

Need I say more.

Tom.

EastPete · 5th October 2018, 08:48

I have just finished the welding on the NS sill on my MGB GT - spot welded across the door opening and plug welded elsewhere . The originals spot welded. My car does not require an MOT anymore, but I will get it tested when I get it back together, for peace of mind.

Pete

geavsie · 20th May 2021, 14:41

Quote:

Originally Posted by andymc

I'm interested in getting some feedback from those in the know about welding. I had to replace the entire length of both sills on one of my cars after I'd left it standing for just over a year (other than starting it & taking it up and down the lane every few weeks). You live & learn ... Anyway, I took it for MOT last week and it was failed because the tester said it had to be seam-welded along the full length of the sill, as opposed to being spot-welded and then filled. When I took it back to the garage, they expressed surprise at this and said that seam-welding wouldn't even have been done in the factory, let alone for repair work. They also said that with seam-welding, due to the expansion and contraction of the metal as it is heated and cooled, there was a risk of creating a "twist" in the body of the car unless care was taken to avoid this by doing the job in stages.

They aren't refusing to take on the job, but I'm obviously not keen to pay for unnecessary work to be done either. I'm not knowledgeable enough about this to have an informed opinion, so I'd welcome input from those who know what they're talking about.

NB I'm in NI, which means the MOT stations are government-run and never do any repair work - their sole job is to do the testing. There's no chance whatsoever that the MOT tester is trying to generate work for himself.

The MOT station was wrong. Seam welding is the preferred option, and spot welding should only be used where it is replacing existing spot welds.
Take a look at

https://www.gov.uk/guidance/mot-insp...-and-corrosion
You can only pass spot welded repairs if the original panel was spot welded and the original panel or section has been removed. Stitch or plug welding can be used instead of spot welding.
In all other circumstances, patch repairs must be continuously seam welded.
Some vehicle manufacturers have recommended repair methods that use MIG brazing, a combination of adhesive bonding and riveting, or amalgamations of these with other joining methods. Such repairs are therefore acceptable unless they are clearly inadequate.

3rd October 2018, 14:44	#1
andymc Posted a thing or two Wedgewood Connie SE / Black Club SE Join Date: Jan 2014 Location: Ballymoney Posts: 1,459 Thanks: 542 Thanked 583 Times in 365 Posts	Seam welding of sills? I'm interested in getting some feedback from those in the know about welding. I had to replace the entire length of both sills on one of my cars after I'd left it standing for just over a year (other than starting it & taking it up and down the lane every few weeks). You live & learn ... Anyway, I took it for MOT last week and it was failed because the tester said it had to be seam-welded along the full length of the sill, as opposed to being spot-welded and then filled. When I took it back to the garage, they expressed surprise at this and said that seam-welding wouldn't even have been done in the factory, let alone for repair work. They also said that with seam-welding, due to the expansion and contraction of the metal as it is heated and cooled, there was a risk of creating a "twist" in the body of the car unless care was taken to avoid this by doing the job in stages. They aren't refusing to take on the job, but I'm obviously not keen to pay for unnecessary work to be done either. I'm not knowledgeable enough about this to have an informed opinion, so I'd welcome input from those who know what they're talking about. NB I'm in NI, which means the MOT stations are government-run and never do any repair work - their sole job is to do the testing. There's no chance whatsoever that the MOT tester is trying to generate work for himself. __________________ My blood brother is an immigrant A beautiful immigrant My blood brother's Freddie Mercury A Nigerian mother of three

3rd October 2018, 15:23	#2
RoverP480 Gets stuck in None at the moment Join Date: Jan 2018 Location: Hereford Posts: 501 Thanks: 1 Thanked 165 Times in 146 Posts	The factory would be spot welded if that has been done for the repair I cannot see the tester would fault it. Extract from NI test criteria. Suitable materials of appropriate gauge or thickness should be used for repairs so that: • Any plating or welding extends to a sound part of a load bearing component, and • The repair must be virtually as strong as the original structure. So only a continuous seam weld is acceptable for patch repairs (even if the patch extends beyond the prescribed area), although spot welded joints are acceptable where they originally existed (provided the original defective panel flange has been removed). Stitch or plug welding is acceptable as an alternative to spot welding in these cases. https://www.infrastructure-ni.gov.uk...ion-dvt938.pdf I don't understand the " then filled" bit in your post Last edited by RoverP480; 3rd October 2018 at 15:49.. Reason: extra info

3rd October 2018, 17:22	#3
cbr1100xx Gets stuck in VW touareg Join Date: Mar 2015 Location: dunsop bridge Posts: 870 Thanks: 225 Thanked 414 Times in 235 Posts	As I understand it , if you replace the whole sill panel then spot welds will do as they were used originally. If its a repair patch then it has to be seam welded to make a continuous join . Stan __________________ WE WERE BOTH BORN ON THE 4th of JULY CAR DIED 15/11/2022---I'M STILL GOING (JUST)

3rd October 2018, 17:51	#5
philm Loves to post rover 75 tourer Join Date: Jan 2017 Location: HEREFORD Posts: 269 Thanks: 7 Thanked 69 Times in 56 Posts	From the welding for MOT,S i have done in the past the top section of the sill where it joins to the original bodywork needs to be seam welded the lower part of the sill can be stitched or spot welded every couple of inches as manufactured but they are always changing the regs. __________________ Free Toaf & Delphi diagnostics.

3rd October 2018, 17:52	#6
philm Loves to post rover 75 tourer Join Date: Jan 2017 Location: HEREFORD Posts: 269 Thanks: 7 Thanked 69 Times in 56 Posts	Beat me to it Brian __________________ Free Toaf & Delphi diagnostics.

3rd October 2018, 17:47	#4
marinabrian MG ZT Join Date: Jan 2011 Location: Newcastle Upon Tyne Posts: 20,151 Thanks: 3,565 Thanked 10,837 Times in 5,718 Posts	A patch must be seam welded around the periphery area where it adjoins the original panel, however the part that abuts the adjacent panel where spot welds were employed originally may be plug welded or spot welded. This has always been the case, however a continuous weld may consist of a series of stitch welds, as long as they form an unbroken seam. This is important, as panel heat distortion is normally avoided by this type of repair. Brian

4th October 2018, 11:35	#7
andymc Posted a thing or two Wedgewood Connie SE / Black Club SE Join Date: Jan 2014 Location: Ballymoney Posts: 1,459 Thanks: 542 Thanked 583 Times in 365 Posts	Many thanks folks, I'll pass on those responses. __________________ My blood brother is an immigrant A beautiful immigrant My blood brother's Freddie Mercury A Nigerian mother of three

4th October 2018, 15:52	#8
Organiser I really should get out more....... ZT-T+180 Auto & ZT-T+1.8T in Trophy Blue, ZT-T CDTI+135 Auto in Ignition Blue, ZT-T+190 in Typhoon, Join Date: Mar 2013 Location: Walsall Posts: 2,035 Thanks: 1,435 Thanked 600 Times in 467 Posts	MOT Standard Welding. Someone once phoned me up must be 25 odd years ago and asked me if we did mot standard welding, I told him that we did not, when he expressed suprise at that being a bodyshop, I told him we didn't do welding that badly! Need I say more. Tom. __________________ Remember a Typhoon is for life not just Christmas! Now plus the Yellow Peril.