snubengr
Mechanical
- Apr 3, 2002
- 23
Does anyone have experience with EUE tubing, especially L-80, at all sizes, being made up to the specs given in 5C1 and finding that it is just way too high?
Over the years, I have come across this several times, and now again recently with 2 7/8" 6.50# L-80.
After looking at the derivation of these values, which come from 1% of the Round Thread Casing Pull-out Strength (Bull. 5C3: 4.1.2) I am wondering if this is really a valid way to calculate pull-out strength and/or make-up torque for smaller tubing with upsets. I think that the formula they use could give unrealistically high values for pullout strength with this type of connection. Actually, I made a spreadsheet and could not duplicate the values published in RP 5C1 with the formulas and method given by 5C2 and 5C3. Don't know if it my error or what, but I had to fudge the nominal pipe OD value upwards about 7% in every case to get the API values.
We did some research with some local service and rental outfits and found that the tech. data they send out with their EUE tubing almost invariably contains make-up torque values significantly lower than that recommended by API, in some cases up to 50% lower.
So, I guess I have several questions:
1) Does anyone else have experience/insight into this topic?
2) If the values do need some review, how would I approach this with API, or would they even take it seriously? I mean, this method of calculating make-up torque is at least 20 years old. Surely, if this was really a problem someone would have mentioned it by now?
Cheers,
SnubEngr
Over the years, I have come across this several times, and now again recently with 2 7/8" 6.50# L-80.
After looking at the derivation of these values, which come from 1% of the Round Thread Casing Pull-out Strength (Bull. 5C3: 4.1.2) I am wondering if this is really a valid way to calculate pull-out strength and/or make-up torque for smaller tubing with upsets. I think that the formula they use could give unrealistically high values for pullout strength with this type of connection. Actually, I made a spreadsheet and could not duplicate the values published in RP 5C1 with the formulas and method given by 5C2 and 5C3. Don't know if it my error or what, but I had to fudge the nominal pipe OD value upwards about 7% in every case to get the API values.
We did some research with some local service and rental outfits and found that the tech. data they send out with their EUE tubing almost invariably contains make-up torque values significantly lower than that recommended by API, in some cases up to 50% lower.
So, I guess I have several questions:
1) Does anyone else have experience/insight into this topic?
2) If the values do need some review, how would I approach this with API, or would they even take it seriously? I mean, this method of calculating make-up torque is at least 20 years old. Surely, if this was really a problem someone would have mentioned it by now?
Cheers,
SnubEngr
