Machine certification

By pipewelder_1999 (****)

Date 06-21-2008 03:47 Edited 06-21-2008 03:53

I am not on the latest trends in high end welding. As far as ASME Boiler and Pressure Vessel Code goes, there is no requirement for "Certifying" a machine. In some cases there may not even be a requirement for calibration of a gage. Below is an interpretation clarifying what appears to be a conflict between section IX and section III.

The word "Calibration" or "Calibrate" is never used in D1.1 except in reference to Ultrasonic testing. It is not used in ASME Sec IX. However that does not mean the use of a calibrated instrument is a bad idea. The term certified in relation to a welding machine is never referred to in D1.1 Sec IX, Sec I, Sec VII, B31.1.

By whatever method you control the welding process is what you should do. Just be careful on how detailed you get. A ammeter and voltmeter may be all y ou need.

Here is a page I made with a couple of code interpretations with the word calibrate in them. Some interesting reading. http://www.weldinginspectionsvcs.com/requirement_for_calibrated_weldi.htm

I would love to hear some other input on the "code requirements" for calibrating a machine.

See also
http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=63297
http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=32645
http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=18419

You nuclear guys, is there a requirement to have calibrated gage on a welding machine ? does each weld being made have to have the amperage and voltage recorded ?

By ctacker (****)

Date 06-21-2008 04:44

Not sure about code requirements, but its our company requirements that all welding and inspection tools are calibrated, every 6 months I have to calibrate the welders and once a year the meter I use to do the calibration! that was a req. back when we were doing nuke work, and hasn't been changed since!

By jon20013 (*****)

Date 06-21-2008 04:57

Shaking some cobwebs loose, calibration of welding machines was required by D1.1 until sometime in the late 1980's or early 1990's. I "think" it might now be required by AISC, which seems to have gone off the deep end in their quality program requirements, IMHO.

In my former employment, a nuclear fabrications shop, I used to have this question from auditors all the time. I was once asked if it were a manufacturer's "recommendation." Thankfully, for the equipment we had at the time the manufacturer was mute on this subject as I believe most would be.

To satisfy external QA types, I began "periodic" monitoring and recording of parameters using calibrated amp / volt meter. This actually worked to my benefit by showing me when the machines needed some type of maintenance. I somewhat arbitrarily used a plus or minus 10% as my key (there are some welding variables in ASME IX that indicate a plus or minus 10% for such parameters). Of course, we also used a calibrated instrument whenever qualifying new procedures, but not for performance qualifications.

Two cents more. Good posting Gerald, glad to see those interpretations!~

By Richard Cook (**)

Date 06-23-2008 13:45

For my sanity, I seperate "Calibration" and "equipment verification"

AISC requires the AWS standard be applied and the only calibrated instrument is the unit (multimeter) that is used to "verify the accuracy" of you welding machines. The welding equipment must be addequate to perform it's function. The machine itself can have a chart showing a correction factor, if the meters are not functioning then perminent markings can be placed on the adjustment knob to show the range to use.

The welding equipment itself need not be calibrated as per AWS and AISC.

The equipment has to be verified on a regular basis, the arguement is how do you expect the welder to follow the WPS if he doesn't know what his equipment is running. (like they pay attention to that anyway)

By js55

Date 06-23-2008 17:23

I'm with Richard on the calibration/verification dichotomy and use that language in my manuals as well. I do not calibrate welding machines. I verify them.
How do you calibrate a circuit board?

By ctacker (****)

Date 06-24-2008 04:00

when I "verify" our equipment and it doesn't check out, A red tag goes on it and maintanance gets it, the either put new gauges or adjust them until they are accurate. some of the old linde's have a steel bar with an aligator clip attached that slides up and down to adjust the gauges, the millers have a circuit board that has a pot you can adjust. them linde's seem to always need adjustment from rolling on the floor and vibrating the clip down.

By swsweld (****)

Date 06-22-2008 19:19

Gerald, back in my nuclear days we calibrated our machines every time we relocated them. Amps, volts, wire speed and travel speed. Referring to machine welding not manual welding machines. By relocate I mean breaking down, rolling up and relocating them. The cables are sensitive and if damaged they can seriously changed the functions. Not saying total calibration always took place.

To be honest I don't know if that was a code requirement or a company QC/QA requirement; or both.

On some jobs where heat input was critical we were required to show all welding settings (pri/sec amps, pri/sec volts, wire speed, etc.) printed out from the calibrated machine so calculations could be done. As opposed to hand written logs kept by the welders.

By jrw159

Date 06-23-2008 13:38

gshuma,
Does IAS, AISC or ISO play a role in this?

jrw159

By gshuma

Date 06-24-2008 22:51

Thank you
I'll find out where they need to go with this.

By bozaktwo1 (***)

Date 06-23-2008 16:42

In some aerospace specs calibrated machines and power sources are required.