Not logged inAmerican Welding Society Forum
Forum AWS Website Help Search Login
Up Topic Welding Industry / Inspection & Qualification / Volts travel speed for smaw process
- - By joe pirie (***) Date 03-22-2011 18:50
Hi i recently wrote a couple WPS for a contractor using the SMAW process
the inspector of record is insisting that a voltage and travel speed be given.
Lincoln Electric does not provide this information in their product data for smaw
only for gmaw and fcaw. correct me if im wrong smaw is generaly run in cc mode  most  wire operations
are run on CV.  therefore it is not possible to give an accurate voltage reading for the smaw process
as the volts would vary. please advise asap  thanks  joe
Parent - - By jwright650 (*****) Date 03-22-2011 20:08
Joe,
You will get a bouncing needle when you try to measure the welding voltage...I just try to figure out where the middle of the bounce is and use that, I think some volt meters have filters in them to help you figure the median. My A/C machines run around 26-28volts @ 190amps using 5/32" E7018.

travel speed is easy...use one of these methods
time for 15 secs and measure the length of the weld and multiply by 4 to get inches/min.
time for 20 secs and measure the length of the weld and multiply by 3 to get inches/min.
time for 30 secs and measure the length of the weld and multiply by 2 to get inches/min.
Parent - - By Shane Feder (****) Date 03-23-2011 00:01
Joe,
Table 4.5 states (by omission of an X) that measurement of voltage and travel speed are not applicable to the process (SMAW).
Why would you have to record something that is not applicable ?
More to the point, what benefit is it going to be to your welders ?
Every time a welder lengthens his arc a little too much he is outside the WPS range. Every time he wants to put a little, fast bead down the edge of a weld he is outside the range of the WPS,
Regards,
Shane
Parent - - By OBEWAN (***) Date 03-23-2011 01:08
For most impact qualified procedures heat input in Joules or kiloJoules must be controlled.  The control is usually a maximum worst case do not exceed limit.

The exact voltage is not that important as long as an approximate value is estimated.  However, amperage is the variable that is set by the operator and it can be controlled.

So for the PQR the worst case heat input is recorded and then a range is stated on the WPS.  I don't think the operator is expected to use a calculator.  That is why it is important for a valid range to be stated on  the WPS based upon the PQR limits.

And just a reminder for those who might have forgotten.  Heat input is: (amps x volts x 60)/(travel speed).  It is usually listed in kJ/in or kJ/mm.

This is the most common foul-up on the WPS submittals we see every day.  I got one today where the WPS had a heat input allowance of twice the heat input qualified on the PQR.  Not a problem?  Who knows?  More heat means bigger grains.  Bigger grains mean poor toughness.   In some cases at the extreme limits it could cause impact tests on a PQR or real world weld to fail.
Parent - - By eekpod (****) Date 03-23-2011 10:18
Explain to the inspector that volts is not a requirement for SMAW,and show him the table. Also the manufacturer does not give a "range" to be kept within anyway, so how could you write a pre qualified procedure using the manufacturers recomendations, if there is no recomendation from the manufacturer to follow? This guy sounds like he's mixed up. Good Luck
Parent - By OBEWAN (***) Date 03-23-2011 10:37
Heat input is Joules is a spec requirement for all impact tested WPS/PQR documents for ASME, B31.3, and AWS D1.1 and a slew of other codes.  It may seem only academic, but it has to be calculated when the procedure is qualified.  It does not take a lot of effort with the right meter.
Parent - By Duke (***) Date 03-25-2011 19:28
I posted this in "Cert/Qual"...
Code is D1.1 -08
CVN impact testing is required.
10+ passes on PQR
WPS Heat Input value is average of Heat Inputs/individual pass from PQR.
is this right... and where in the code does it state to use average?
Parent - - By jwright650 (*****) Date 03-23-2011 11:52
Joe,
If this is a pre-qualified WPS, then to go along with what Shane has posted, check out AWS D1.1:2010 Table3.8 (12) & (14). These items are greyed out for the SMAW process, so no need to recored them per the Note at the end of the table....as long as you are within the electrode mfg's recommended parameters, I think you are OK.

If heat input is to be controlled then you have a whole different set of issues.
Parent - - By OBEWAN (***) Date 03-23-2011 13:03
Usually the heat input control is only required if there are impact testing requirements and that is sometimes added by the customer above and beyond the spec.
Parent - - By joe pirie (***) Date 03-23-2011 13:18
Hes not asking for heat imput only the voltage and travel speed i tried to explain to him that this was not required
for smaw process but he keeps insisting on numbers being filled out. i emailed him a copy of table 4.5 showing parameters for the
various welding processes. I also sent lincoln electrics product data sheet which does not show voltage and travel speed for smaw.
I  also sent a copy to the Engineer of record hopefully this closes this issue.  thank you all for your assistance  Joe
Parent - - By eekpod (****) Date 03-23-2011 20:20
not to be a smart ass but if he wants a number.... put a 0 in there.  Tell him that's the value that's called for.  I hate when people get stuck on issues like this and won't listen to reason, it makes for a long day when that happens. Good Luck
Parent - - By Shane Feder (****) Date 03-24-2011 00:52
Guys,
A bit of assistance if possible please.
I will use the Kobelco LB52 SMAW electrode as an example.
Manufacturers recommendations for 3.2 mm in VU position 80 - 120 amps.
If I qualify a PQR with testing as per Section 4 can I use 130 amps ?
I understand if I qualified a PQR between 80 - 120 amps and I wanted to then weld at 130 amps it would be a "change" in essential variables which would require requalification.
But what governs initial qualification ?
A bit confused as if it only states "manufacturers recommended range" and I can prove that amps just outside that range can produce a visually acceptable and mechanically sound weld, am I in breach of the code ?
Regards,
Shane
Parent - - By joe pirie (***) Date 03-24-2011 13:23
I believe since your going to weld  a test under section 4 you can use any parameters
you want . simply record the actual amperage used by the welder for the PQR  after
all the required testing is completed and passed your WPS is now approved.
I think the initial qualification is based on the manufactures test reports.
Parent - By welderbrent (*****) Date 03-24-2011 14:52
I agree with Joe,

When doing a qualification by testing you can choose the amps.  But you need to be more specific than for the WPS.  It would be a fixed amount such as '130' as you stated and not a range as you would use on the WPS.  I believe the 2010 D1.1 states a wider range is then usable so that the WPS could be 120-140 amps after successful testing at 130 amps.

For a pre-qualified WPS the range would need to remain within the manufacturer's recommendations of 80-120.

At least that is how I read it.  And pretty sure that is how it was just taught this week at the Code Clinic I sat through.

Have a Great Day,  Brent
Parent - By 99205 (***) Date 03-24-2011 05:10
Not sure if a 0 would be a good thing to do because it could be construed as a value.  I would probably put a N/A in that section.
Up Topic Welding Industry / Inspection & Qualification / Volts travel speed for smaw process

Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill