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Up Topic Welding Industry / General Welding Discussion / 410 CA6NM (casting) to 304 weld neck flange (forging)
- - By engineer1984 (*) Date 07-09-2019 17:25
Hi,

I need to weld a 304 weld neck flange to a 410 CA6NM casing without PWHT.  I'd like to use 309L as the filler, but open to suggestions.

This weld is purely a seal weld and does not need strength.  HAZ is not really a concern either, this is a low stress area.  My main concern is cracking in the 410.  Can I solve this using a pre heat of 500 F and an interpass temp of 700 F max?  .

Our company does not have a P#6 to P#8 WPS, I am currently eyeing different prospects for my first WPS.  Perhaps this is the one I will be doing in the future.
Parent - - By engineer1984 (*) Date 07-09-2019 17:37
After reading a bit more, it seems that a low Pre-heat is better than a high pre-heat with CA6NM if one is using an austenitic filler material

I am referencing:

https://app.aws.org/forum/topic_show.pl?tid=6892

https://www.usbr.gov/power/data/fist/fist2_5/vol2-5.pdf
Parent - - By engineer1984 (*) Date 07-09-2019 21:03
ASME VIII requires P# 6 a minimum pre heat of 400 F.
Parent - - By Jim Hughes (***) Date 07-10-2019 14:54
Good for you engineer1984, seems the more you dig the more you answer your own questions. I would keep going in that direction. You are doing the things anyone would do before qualifying a welding procedure. Gathering data to make sure it's done correctly.
Parent - - By engineer1984 (*) Date 07-10-2019 17:00
Thanks,

To get the weld started (I don't have time for a WPS for this particular contract), I gave a very brief set of requirements and let the welder decide on machine settings, speed, etc.

Process:             GTAW
Filler:                  309L
Pre heat:            400F + 50 F
Max Interpass:   500 F
Gas:                   100% Argon

Otherwise, pretty much left it up to the welder.
Parent - - By Shane Feder (****) Date 07-15-2019 12:38
Firstly,
How can a weld neck flange to a pump casing be a "seal weld" ?
What code does this weld have to comply with ?
Strongly recommend you get a Welding Engineer involved before you go any further as it is not as easy as you seem to think (just leave it up to the welder ?)
We welded 316 nipples to CA6NM pump casings years ago and the time and cost involved was astronomical.
Try getting CA6NM coupons for a start.
Then we had to "butter" the CA6NM, PWHT that and then weld the 316.
What makes you think you do not have to PWHT CA6NM ?
Parent - By engineer1984 (*) Date 07-15-2019 14:48 Edited 07-15-2019 17:10
We weld the weldneck flange to a pipe (both austenitic) and then slip the piping into a bore in the casing.  Circumferential fillet weld around piping / casing (Socket weld). 

ASME BPVC is what we use.  Ultimately, API is what we deal with.  API references ISO 10440 (I think this is correct, didn't double check.  ISO is geared towards purchasers, not OEMs) and ISO references ASME BPVC. 

Leaving weld speed, amperage, cup size, argon flow up to the welder.  We have very experienced welders.  We do NOT have time for a WPS / PQR for the immediate problem.

I'm not sure why I would need PWHT CA6NM in this specific application.  I'm aware of cracking that can occur during welding (we have weld repaired these casings before).  We may be able to locally PWHT the area.  What reasons are there for PWHT'ing this area?  This is a low stress, low vibration, low corrosion area. 

What did you butter the CA6NM with? 

Cheers,
Up Topic Welding Industry / General Welding Discussion / 410 CA6NM (casting) to 304 weld neck flange (forging)

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