weldinguide.com

all about welding





Max interpass temperature vs time lapse for hot pass

Max interpass temperature vs time lapse for hot pass

Postby smilepls » Sat Nov 09, 2013 11:06 am

dear experts,

In E6010+E7018 WPS as per API 1104, we have maximum interpass temperature 250 degree C & the hot pass shall be made within 10 minutes of root pass. Is it required to check the temperature before hot pass? Shall it be max 250 degree C? I mean if within 10 minutes the temperature does not come to 250 degree C then what to do?

Which criteria is more important max interpass temperature 250 degree C or 10 minutes time lapse between root pass and hot pass ?

regards
smilepls
 
Posts: 2
Joined: Wed Oct 23, 2013 5:50 am

Re: Max interpass temperature vs time lapse for hot pass

Postby mohd » Sun Nov 10, 2013 2:46 am

dear one,

Q1: Is it required to check the interpass (IP) temperature before hot pass?
A1: Yes. It is a very routine practice adopted by welder and in process QC.

Q2: Shall it be max 250 degree C?
A2: Yes. As you have mentioned it is established in WPS.

now a tricky question,
Q3: What if IP temperature not reach 250 degree C in 10 minutes?

Since SMAW involved, I suppose that the production base metal thickness is more than 10 mm as well as preheating doesn't apply (welding at ambient temperature).
I presume 10 minutes time is not a code requirement.
I assume as you mentioned the WPS qualified for 250 degree C and 10 minutes lapse time.

A3: As we know the root welding needs higher current for good root penetration. Welder can do root welding with more interruptions (means rest time /electrode run) to maintain the required IP. So hot pass can continue within 10 minutes.
Another thing you can do is to go for GTAW root welding if possible as per your situation.

Q4: Which is more important IP or time lapse?
A4: As I said time is not code requirement, time is what we established during qualification to achieve the required IP. Hence IP is considered to be more important with respect to the time lapse.

regards,
mohd.
mohd
 
Posts: 74
Joined: Mon Jul 08, 2013 2:17 pm


Return to Pipelines and related facilities welding

Who is online

Users browsing this forum: No registered users and 1 guest

cron