Interpass temperature

By jon20013 (*****)

Date 06-07-2007 09:30

ASME IX doesn't tell you when to take interpass but in my opinion it doesn't need to be taken after evey stop/start although thats what I do when running a PQR it seems a little excessive for fabrication/construction. It needs to be monitored and should be done so at intermittent stages. Keep in mind the interpass temperature may, during welding operations, go higher than whats listed on the WPS. This simply means the welder must wait for the part to cool before beginning another bead.

By thesmiths1969 (*)

Date 06-07-2007 10:45

I have just been talking to a few Welding Engineers I work with for other companies and they tell me that you must put your root run in first. You then check the Interpass Temperature were you are starting your hot pass or fill if within interpass temp specified then you can weld. After this every stop start is checked for every stop / start.

By jon20013 (*****)

Date 06-07-2007 11:50

Different strokes for different folks. By definition, interpass is the temperature taken before laying additional passes so it could be taken after the root, after each bead or pretty much wherever the inspector wants to take it. In my own experience it isn't all that common to approach maximum interpass but that said it pays to check at various intervals.

By js55

Date 06-07-2007 14:54

The language of 'Interpass" is not chosen without consideration. And it is exactly that. 'Inter' pass. Not 'intra' pass, not constant. It must be kept in mind that interpass temps are a minimum regulatory process. It does not mean that as soon as you violate this temp that there is some irreversible damage to the material. There are very few alloys in which this is the case. And the code tries to minimize being too alloy specific, or being too 'cookbooky'. Would you really want to pay for 20 volumes of ASME IX?
An Engineer is certainly free to impose more stringent requirements if they deem it necessary but this isn't the intent of the word or the requirement.

By bozaktwo1 (***)

Date 06-07-2007 17:21

I had always been taught that the interpass temperature is to be taken immediately prior to starting the next pass. If it is below spec, but close, say within 10%, then we had to let it cool. That's all HY80 though. Not sure about any non-MILSPEC requirements.