Help - Search - Members - Calendar
Full Version: Tips On Welding Duplex
Welding Forum > UKWelder > Practical Welding Questions
DUNNY
Hi. I am looking for some advice and tips about welding Duplex.
Is it like welding stainless steel ?


Some advice would be appreciated
Screaming Juice
QUOTE (DUNNY @ Mar 28 2006, 08:13 PM)

Is it like welding stainless steel ?



Yes.
DEEP PEN
hi
when your rooting double dip your wire
apart from that its the same as ss


The Fish
I would say double dip, wash across and walk the dog.
kaynakci
QUOTE (DUNNY @ Mar 28 2006, 07:13 PM)
Is it like welding stainless steel ?

No.

Unlike welding ordinary stainless - I assume you mean austenitic stainless - it is essential that your interpass temperature does not exceed 200C. Failure to do so will result in the job or test-piece failing any relevant corrosion test.

kaynakci.
rodofgod


Hi All!

DUNNY!

I'm no Duplex expert but I have done a few procedures in my time! It is like S/S regarding purge etc. Feels a bit different welding than 316 or whatever, however the main difference in passing a test or performing adequate welds is the 'heat input'!

From a welding point of view, Duplex is a little different than normal S/S but the main point is keeping heat input down! That means below the temp on your procedure!

Regards

nigel 42
i think somewhere in the past this subject has been covered
perhaps it was with mig
and rofgod is right
nanjing2
Duplex is stainless steel but it cannot be welded without a great deal of care. When welding the golden rule is simply travel as fast as possible to keep the heat input down. Always follow the WPS. Thin section 25% Cr Super Duplex interpass temperature may be as low as 75C.
wavey dave
Go Weir Metals website there is lots of info on it about welding duplex.
Captain
Agree with other posts.
You've got to watch your interpass temperatures!
Duplex is typically 150 degrees C, whilst Super Duplex (Zeron) is typically
100 degrees C.
Always refer to your procedure, it will tell you what the interpass temperature is.
Captain
DUNNY

Thanks all.

I have a test piece tomorrow. Talk about throwing yourself in the deep end.
Maqius of Argon
QUOTE (DUNNY @ Mar 29 2006, 09:41 PM)
Thanks all.

I have a test piece tomorrow. Talk about throwing yourself in the deep end.

heerema by any chance
WELDAAAA
TURN YOUR PURGE GAS HIGHER THAN WELDING SS
zap
weld it like stailess , if its only being bombed dont worry too much about the interpass heat , however if it will be subjected to mechanicals then keep an eye on your heat input. straight forward really.
nanjing2
If you follow Zap's advice you will fail your test.
zap
only been doing it for the last 25 years !!!!!!
nanjing2
Zap you are telling someone to do something that is clearly wrong. 25 years experience or not. Do this on your test and the inspector will have your test terminated.
beads r us
QUOTE (zap @ Mar 30 2006, 09:00 AM)
only been doing it for the last 25 years !!!!!!

zap 25 yrs welding and you dont know how to test out shame on you (te hee hee)
Screaming Juice
i can't remember an inspector checking temp during a test, duplex or otherwise.
but i know procedures are different.
so im curious, can the inspectors on here tell us if they check temperatures when welders test out?
rodofgod

Hi All!

In the 'old' days, you would have got away with this, you might still do so! However, all the time Inspectors are being given more and more responsibilities and pressurized to perform multi-tasking! The client companies have realized that they can demand more for their than ever before!
If you follow the advice of zap then you will eventually come across such an inspector!
It's up to the individual, weld according to the procedure or 'risk' it and do it your way! You may have passed a 100 test's doing it your way but the one you don't is the one that count's!
Two years ago,on a job, I was required to perform 'Heat Input' calcs on every test piece (C/s,S/S and Duplex) and 10% of site welds per welder! Just a sign of the times!
Regards
zap
And how many of the heat inputs needed the figures massaged to fit the clients spec ?????? We all know what is "right " Im just saying that in most cases you will be ok welding it as per stainless however some people love to over complicate welding .
mossy282
Screaming juice

It depends on the procedure,if temp is a critical factor then yes i have been asked to check temp at every stage of the test,years ago this was rarely done but as it has already been said,sign of the times.Welders should be aware of this trend as i have had some very irate welders when i have failed them for excessive heat input during their test.
mossy282
nanjing2
QUOTE (Screaming Juice @ Mar 31 2006, 06:26 AM)
i can't remember an inspector checking temp during a test, duplex or otherwise.
but i know procedures are different.
so im curious, can the inspectors on here tell us if they check temperatures when welders test out?

Its not the inspectors job really to check the temperature, he should be watching the welder to see if he checks the temperature. If the welder doesn't even have a digitherm the test shouldn't be allowed to start.
nanjing2
QUOTE (zap @ Mar 31 2006, 05:00 PM)
And how many of the heat inputs needed the figures massaged to fit the clients spec ?????? We all know what is "right " Im just saying that in most cases you will be ok welding it as per stainless however some people love to over complicate welding .

Zap if you really want to improve your knowledge of welding duplex you should think about taking a course to try and get a better understanding. You can really screw the stuff up quite easily, its nothing like welding something like 316. Remember passing the "bomb" isn't the be all and end all. If it's not welded correctly it will fail in service.
zap
get your hand off it man , I am doing it on a daily basis ...... over complication anybody??????
zap
i seem to remember one of your postings from before which explained that you are not a welder .... nuff said
kaynakci
Zap,

I have to agree with nanjing. If you don't check your interpass temperatures with a digitherm or even a tempil stick then you are going to strip the duplex of its superior corrosion resistance properties. Duplex is used in very demanding environments - usually offshore - which demand extremely resistant materials.

I do accept your point that welding is sometimes "over complicated". But the observance of interpass temperatures isn't over complication - it is as fundamental as purging a root run when working with this material.

kaynakci.
millsy
Hello all,
Wavey Davey I couldn't find Weir Metals do you have their web address cheers Millsy
melba
THE INSPECTERS CHECK ON US REGULAR , DID YOU REALISE DUPLEX TENDS TO SHOW PORES WHEN ITS BEEN OVER MAX INTERPASS AND CAN SHOW GRANULER CORROSION RUST ON HAZ WITHIN DAYS OF WELDING . WE BEEN DOING LOADS HEAVY WALLERS, 1ST 4 RUNS ALL ARGON THEN SQUIRTY, THEY SHARP GO DOWN IF THEY BEEN TOO HOT, WE TRY DO 2 OR 3 TOGETHER ITS EASIER HERE IN PIPE SHOP BUT ON SITE WHEN THEY BREATHING DOWN YOUR KNECK TO GET THEM DONE ,WELL THATS WHEN PROBLEMS START , YOU HAVE TO TRY AND KEEP A HAPPY MEDIUM WITH PRODUCTION AND INSPECTION, AND ALLWAYS REMEMBER THIS IS ONE OF WORST METALS FOR YOUR HEALTH WE ALL SUFFERING BOILS AND NOSE BLEEDS , AND WE GOT AIR FEDS,
zap
just had a look at our procedures for welding duplex as opposed to welding 316 ss max interpass 150 for 316 and also for duplex . kj/mm figures the same also , so I think the advice to weld it similarly to 316 was fair advice , spoke to the other blokes here who all say the same thing . Granted ,if you have an inspector over your shoulder every second of the test , you will have to be spot on , but practically for welding it day to day......same as stainless !
zap
would be interesting to hear dunnys opinion after he has done his test
nanjing2
QUOTE (zap @ Apr 1 2006, 04:37 PM)
i seem to remember one of your postings from before which explained that you are not a welder .... nuff said

Yes, thats right I'm not a welder I am an Engineer and employed by the second biggest construction company in the world to make these kind of decisions. If you don't want to learn why bother coming to this site?.... nuff said.
zap
I answered a reply from someone else looking for info on welding duplex , I can do it , can you ????
nanjing2
QUOTE (zap @ Apr 3 2006, 04:03 PM)
I answered a reply from someone else looking for info on welding duplex , I can do it , can you ????

Of course I can do it. Suggest you use the quote button to avoid confusion.
Stupid Welder
Hi all,
my tuppence worth,iam coded Duplex and Zeron 100X,and you must weld it with as low a heat input as pos,you must watch your interpas temp.
your bead should look nice and shiny,if it is grey you have burnt it ,and it will rust and fail chemical tests,and a good inspector will be able to see that in the photos.
You can polish it with a ss brush fitted to grinder and it will look fine,but like i say it will FAIL all tests.
Cheers
SW
tighead
a passing thought.......... has any one looked at the new (i know they've been around a year or 3) pulse on pulse MIG machines
just started doing some work on ali with them they seem v good. Could this not reduce the heat input and also give larger weld deposit thus reducing number of runs? Could they be used with duplex?
zap
QUOTE (nanjing @ Apr 3 2006, 11:22 AM)
QUOTE (zap @ Apr 3 2006, 04:03 PM)
I answered a reply from someone else looking for info on welding duplex , I can do it , can you ????

Of course I can do it. Suggest you use the quote button to avoid confusion.

Dont know which part of the globe you live in ,but where I am theres more money in welding than in being an engineer (project managers gofer ) so why dont you pick up the torch??
nanjing2
QUOTE (zap @ Apr 4 2006, 08:59 AM)
Dont know which part of the globe you live in ,but where I am theres more money in welding than in being an engineer (project managers gofer ) so why dont you pick up the torch??

Zap you better keep quiet where you are- too many hungry welders out there looking for your highly paid job as they are few and far between.
Why don't I pick up the torch? Obvious I think, too many long term high paid engineering (project managers gofers)jobs around.
Another reason is I'm sitting just now in my cosy office, but I sometimes go to the window to look outside, its -40C. Got to make sure the welders outside (turks not brits) are not slacking and trying to use some flimsy excuse about the weather to have a cup of tea. I know its not much of an excuse but I can't weld either (but the guys outside freezing their b*lls off for 12 hours a day on a six month trip in this Siberian version of Butlins don't know this). (trust you won't tell them Zap).
Better go and get myself a nice cup of cocoa before I go to bed (also better check those lazy sods outside are still hard at it or they will be in for it tomorrow).

Nite nite!
zap
unfortunately I wont be able to continue this merry banter as I am on 2 on 2 off and Im about to hop on a chopper and probably wont look at the site whilst Im off till next time adios ................
nanjing2
Have a good trip Zap....
wavey dave
Millsy,
The web address is www.weirclearliquid.com
Captain
QUOTE (wavey dave @ Apr 10 2006, 07:00 AM)
www.weirclearliquid.com

If you look at the Weir site, they mention supplying Super Duplex (Zeron) for the Tweedsmuir project getting tied-back to the Piper Alpha.
The Piper Alpha is no more, (R.I.P. July 1988), the work is on the Piper Bravo.
Captain
weldreader
QUOTE (millsy @ Apr 2 2006, 03:11 PM)
Hello all,
Wavey Davey I couldn't find Weir Metals do you have their web address cheers Millsy
millsy
Cheers for the web address weld reader and wavey it is pretty interesting stuff I still don't quite understand interpass temp can anyone explain it simply? cheers all Millsy
bill
worked with Duplex Super duplex 'Zeron 100x cn22/9 n-b for years,pressure vessels pipe work sub sea valves.Always work to procedure 120 interpass is a safe bet go above max heat input material will lose its properties turn to ferrite.And for that wedding ring root always use J-Prep.Ps dear ZAP joined Jan 06 where have you been?on another Planet.
wavey dave
Millsy,
Interpass temperature is the temperature of the base metal measured approximatley 50mm from the weld,between weld passes in a multi-pass operation.
It is always listed as a maximum,and is usually less than 200 degrees F (95c) above the preheat temperature.
The primary purpose of controlling the interpass temperature is to minimize the welding induced stresses.
A reasonable interpass temperature will also prevent the parent metal from becoming so hot that it anneals the weld deposit causing low hardness and strenght.
The corrosion resistance of duplex relies on the balance of ferrite and austenite which should be 50/50 overheating with too slow cooling rates will affect that balance and therefore the corrosion resistance.
Harweld
Hi,

a good site to visit and download information is:-

www.gowelding.com

The papers on duplex are great.

Harry
nanjing2
QUOTE (wavey dave @ Apr 18 2006, 07:49 PM)
Millsy,
Interpass temperature is the temperature of the base metal measured approximatley 50mm from the weld,between weld passes in a multi-pass operation.
It is always listed as a maximum,and is usually less than 200 degrees F (95c) above the preheat temperature.
The primary purpose of controlling the interpass temperature is to minimize the welding induced stresses.
A reasonable interpass temperature will also prevent the parent metal from becoming so hot that it anneals the weld deposit causing low hardness and strenght.
The corrosion resistance of duplex relies on the balance of ferrite and austenite which should be 50/50 overheating with too slow cooling rates will affect that balance and therefore the corrosion resistance.

Interpass temperature should be measured on the weld (pre-heat measured on the base metal). Phase balance between 70-30 is usually accepted for the weld metal.
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.
Invision Power Board © 2001-2014 Invision Power Services, Inc.