Inspection of individual piece parts feature in the assembly 2

[Ali121]

Hi guys,
I need help on the requirement of inspecting individual piece parts features on to the assembly level in the same drawing.
For example: We have a drawing which have 3 piece parts having holes with positional tolerances at piece part level and the assembly of those parts by welding with different part number in the same drawing.
All piece parts and assembly are in the same drawing.

We have a conflict on making and inspecting some of the feature like hole drilling and inspecting position of the holes called out on the piece part number after the assembly due to some distortion that can happen after the welding.

I understand that manufacturing sequence can be changed as per convenience.
But I want to know that as per standard is it mandatory for a supplier to follow this or designer should think to move the features on the assembly part number if there is a chance of distortion.

Can you guys help me in answering this with the reference of applicable ASME section,

Thanks,

 

[CheckerHater]

If I understand correctly, you are having problem with applying positional tolerance to reference dimensions. Don't worry, it's legal.

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[Ali121]

@CheckerHater,
Thanks for your reply.
We have the positional tolerance of holes called out in the piece part level of the drawing which getting change after all parts are welded together due to assembly fit up and distortion due to welding.

We have been asked to not drill these holes on piece part level and perform after welding operation on the assembly.

My question is that as a supplier is it mandatory as per ASME to inspect the positional tolerance of holes on the assembly or its upon my discretion since these holes are not called out on the assembly part number.

I believe if its must be on the assembly than the drawing should be updated to move the holes on the assembly.

Can you provide me any ASME reference that covers it?

Note: These parts and assembly are on same assembly drawing document having different dash numbers.

 

[3DDave]

The standard makes clear that requirements apply only at the drawing level they are specified at. Mainly this is not abused and parts are not typically damaged during assembly, but if they are, then the requirement should be applied to the drawing level above where the damaging operation is done. Individually detailed parts on the same drawing as the weldment are still considered a separate drawing level.

If they have asked, they can negotiate the change in the contract, perhaps including changing the contract by changing the contract drawing.

That said, as the fabricating agent, your company should have been aware that the part would distort in a way to not meet the piece part requirements. You aren't obligated to make that clear, but you would not be in this position had you done so and either made that a line item on the bid or refused the work.

 

[Ali121]

@3DDave
Thanks for your reply, Very helpful,

Would you please recall or provide me the standard specifically covering this statement?

"The standard makes clear that requirements apply only at the drawing level they are specified at."


Thanks,

 

[3DDave]

Fundamental rules: 1.4 in 2009,
(o) Dimensions and tolerances apply only at the drawing level where they are specified. A dimension specified
for a given feature on one level of drawing (e.g., a detail drawing) is not mandatory for that feature at any other level (e.g., an assembly drawing).

 

[Ali121]

@3DDave
Thanks alot. Truly appreciate your support!

 

[jassco]

Hi, Ali121:

Your prints should have only one interpretation. There should be no ambiguity. Can you post part of your print to show what you talked about?

Best regards,

Alex

 

[drawoh]

Ali121,

As far as I am concerned, a weldment is a piece part. You don't care what they weld together or how they weld it, as long as it meets your dimensional requirements and your material specifications.

Are you subcontracting the pieces you will be welding together?

--
JHG