interpass temperature defintion

[ContractHome]

our procedure defines weld pass as a weld bead extending the entire length of a longitudinal weld. The result of a pass is a weld bead and may include several stops and starts.

the procedure definition for interpass temperature as the maximum temperature of a section of the deposited weld metal and adjacent base material immmedialtey prior to welding again in that section for multipass welds.

The location for taking this temperature states 1" from the weld.

However, many of the welder take the deffintion of weld pass and interpret it to read that the temperature should only be taken between weld layers and only at those points. ie prior to root, prior to each intermediate layer and prior to final cover layer.

I believe it means that at no point shall the assembly be above this temperature.

 

[metengr]

Interpass temperature as defined by ASME Section IX;

interpass temperature: the highest temperature in the weld
joint immediately prior to welding, or in the case of multiple
pass welds, the highest temperature in the section of
the previously deposited weld metal, immediately before
the next pass is started.

The interpass temperature is to control the amount of heat into the weld joint, meaning the surrounding base material that encompasses the weld joint.

 

[DVWE]

I believe it means that at no point shall the assembly be above this temperature.

You are correct. However, I would replace your word "assembly" with weld joint.

 

[SJones]

Is the aim of your question to ascertain whether you should be trying to hold your welders to the maximum interpass temperature after a stop and prior to a start?

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[Kiwi2671]

diverdileo,
This is an interpretation from ASME IX
IX-83-161
Question: When interpass temperature (QW406.3) is a required supplementary essential variable for procedure qualification, must the interpass temperature be as specified immediately prior to each arc initiation ?
Reply: No. Interpass temperature shall be as specified immediately prior to the start of each pass.

AWS A3.0 defines a weld pass as a single progression of welding along a joint.The result of a weld pass is a weld bead or layer.

I do not know how to post pictures but for those of you who have access to AWS A3.0 have a look at Figures 23 (D) & (E)- they show details of weld layers.

Sorry to say diverdileo but your welders are correct.
Regards,
Kiwi

 

[ContractHome]

I do not believe my welders are correct because none of them agree among each other. The majority of the welders believe do not believe after each pass, but after a complete layer, but some say it is too control heat input because to much heat is damaging but other say it is to allow the previous weld to cool or temper before laying another layer on top of it.

 

[Kiwi2671]

diverdileo,
This is what you posted

"However, many of the welder take the deffintion of weld pass and interpret it to read that the temperature should only be taken between weld layers and only at those points. ie prior to root, prior to each intermediate layer and prior to final cover layer."

That is correct.

You also posted

"I believe it means that at no point shall the assembly be above this temperature."

That is incorrect

Regards,
Kiwi

 

[ContractHome]

I am not insisting that I was correct in my interpetation of a pass, but they were saying to take it between complete layers and not passes. We all agree that a layer is composed of many passes in a multipass weld. I seem to get alot of responses stating not to take temp between layers exclusively when a layer is completed which most of the welders were stating. All my welders and responders to my post seem to agree what a layer was but I posted this question on other websites and there has been some disagreement what a pass is. I believe the welders and myself were both wrong. My interpetation of a pass did not ryme with the intent of the purpose of interpass temp to control cooling to allow metal to cool before another bead is plassed on top (to allow it to temper)- That makes alot of sense-but I still get many responses that state the "at no point interpetation"The tempering explanation makes alot of sense-but is there anything keeping a welder from getting the material too hot even if they wait for it to cool down before placing the next pass.

 

[metengr]

Section IX definitions------------------

layer: a stratum of weld metal consisting of one or more
beads. See figures QW/QB-492.1 and QW/QB-492.2.


pass: a single progression of a welding or surfacing operation
along a joint, weld deposit, or substrate. The result of
a pass is a weld bead or layer.

 

[DVWE]

Take a look at the definition provided by metengr once more. Simply put, you cannot be above the maximum interpass temperature listed on the WPS before ANY weld pass is started.

A good example would be if you have a WPS with a listed maximum interpass temperature of 600F. You cannot start any weld pass if the weld joint is above that temperature, and you take the temperature immediately before the start of the next weld pass. Now, what if you take the temperature of the weld joint immediately AFTER a weld pass has been completed and the temperature is 625F?
Is that acceptable? YES.
Can you start welding before the weld joint cools to 600 or below? NO.

 

[SJones]

How are the welders getting paid as the incentive to work to an 'interlayer' temperature is that they can probably get their welds completed quicker?

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[Guest102023]

metengr,

Interpass does not limit heat input, it is just the maximum temperature the plate can have before starting the next pass.

One problem with the temperature definition can arise when welding with high heat input (Q) on fairly thin plate, of a material where maximum temperature is an issue (e.g., duplex SS). The temperature during and just after welding can be extremely high and could still do metallurgical damage, even if the welder waits until it cools down before depositing the next pass.

This is another reason not to skimp on the size of PQR test plates, where the heat sink is a 'worst case' condition (i.e., very small).