Tolerances for I and U for WPS

[chti]

Hello,

Iwould like to know what are tolerances for U and I you write on your WPS, according the PQR?
Thank you for your help.
Regards.

 

[MintJulep]

I would list the value that I want the operator to set the dial to, without any tolerance.

Tolerance should be controlled through an equipment maintenance and calibration program. The developer of the PQR should know how far the actual values can deviate from the "Knob".

 

[GRoberts]

It depends on what code the WPS is written to. ASME Section IX, for instance, does not list amps and volts as an essential variable, but AWS D1.1 allows +/-10% on amperage, and 7% on voltage. Others have different schemes.

 

[stanweld]

It depends on the process, power supply, weldment design and the controls you wish to define for the welder or welding operator. It also includes any Code heat input mandates for impact testing, weld overlay, etc.

 

[chti]

hello,


Thank you for your answers. But my question is about WPS required for welding in shoop floor.
In your PQR you define all electrical parameters, and you fix these parameters, for a grade, a thickness, a diameter, number of layers....and you are qualified for these variables.But in shop floor, in the WPS you have to define the type of joint, parameters ....according the PQR, and my question is about tolerances you write for electrical parameters,U and I ? +- 20% ?
Sometimes, some inspectors require for welding the max and mini!
best regards.

 

[stanweld]

I believe that your question has indeed been answered. There is no one-size-fits-all range. It's up to the Mauufacturer based on Code requirements, item(s) welded, welding process and degree of control desired/required. I have seen WPS's with +/- 5%, +5%-0, +/- 20% the range recommended by the electrode manufacturer, etc.

 

[GRoberts]

The code you are using will tell you what tolerances you have. You can set your tolerances tighter at your own discretion, but can't go wider. If you aren't working to a code, there is not an industry wide standard.

 

[hogan666]

It depends on the code. The AWS +/- 10% and 7% have been increased slightly due to an interpitation by AWS

AWS Log: INQ-21
Inquiry: (1) For a prequalified WPS, is it the intent of AWS D1.1:2000 that a single value or mean value
be specified and the limitations of Table 4.5 be applied to the specified value?
(2) For a prequalified WPS, is it the intent of the AWS D1.1:2000 that a range of values may be
specified and the limitations of Table 4.5 be applied to the specified range?
Response: (1) No. Use of a single value or mean value is neither required nor prohibited.
(2) Yes, as long as the range of values is within the range of the manufacturer’s
recommendations, see 5.3.1.2.

 

[pipewelder1999]

ASME Sec IX is liberal with electrical requirements for some processes. A recent interpretation below even indicates it need not be addressed for multiple sizes.

The amperage is to be addressed howver there is nothing that references range or how its controlled. I have been in a few shops where the manufaturer has written into their quality system "Procedures for Calibrating Welding Machines" . Welding machines are not meausuring instruments. The gauges MAY be. The Clamp on Ammeter MAY be. However there is nothing in most of the codes that requires this check to be done. A companies quality system should address this in the "Control Of Special Processes" section in thier manual.

Interpretation: IX-95-18
Subject: Section IX, QW-409.8, Electrical
Characteristics
Date Issued: October 19, 1995
File: BC95-220

Question: Does Section IX require that a
separate amperage range be specified for each
filler metal size listed in the WPS?

Reply: No.

There is a page on my website at

http://www.weldinginspectionsvcs.com/requirement_for_calibrated_weldi.htm

that has some interpretation from ASME codes regarding calibration.

Have a nice day.


Gerald Austin
Iuka, Mississippi

http://www.weldinginspectionsvcs.com