API LTC and STC Make-Up Procedure - Torque or Vanish Point? 1

[johnchrc]

Does anyone know the API Procedure for making up LTC and STC connections? I have seen torques listed but is that just a reference based on Coupling aligning with vanish point. I have torques but don't know the pipe dope used or any particulars, just that it was reported in API RP5C1 1981. This could make a big difference.

I am interested in 4-1/2 and 5-1/2 casing sizes and the most common weights. I'm not positive but I think for 4-1/2 its 11.6,13.5, and 15.1 and 5-1/2 15.5, 17, 20,and 23 ppf.

Does anyone know the proper procedure?

Note: It is for shop make-up for pressure testing but also shop make-up (with torque machine) to handling joints going to the field.



- CJ

 

[VAWTEng]

I have a access to RP5C1 1999. What casing grade are you using? M65, L80, N80, C90.....?

 

[johnchrc]

P110, L80, 13 Cr L80

I need to purchase that manual. We are pressure testing 4-1/2 and 5-1/2 accessory tools multiple times with BTC connection and it is beginning to cause issues with the Bullplug threads and accessory items. The shop wants to use PTFE tape and torque up with 48. It has worked for them in past but I saw the results where they did same thing with an STC premium connection and parted the thread on the lower pin at 12500 psi. You could see where maybe 20 degrees of thread was being loaded unevenly and parted leaving hole and then thread unzipped. BOOM! Saw it on video. I believe the made it up with 5' pipe wrench too so it was lobed at least while torqueing.

I am asking them to remove all piep dope after each test, clean connection and reapply dope. Lot's od resistance but I have had to pull Bullplugs out of service because I found fine long metal shavings and the flanks are becoming rough.

Need internal pressure test fixture. I don't think the threads need to be tested. They are gauged at machine shop.

Just a mess...

- CJ

 

[VAWTEng]

Okay so the recommended casing compounds are explained in API Bulletin 5A2 which i don't have access to. RP5C1 has a note saying casing thread compounds should not be used on rotary shouldered connections. Maybe there is part of the problem? Using RSC compound on casing?

Makeup:
1. The correct makeup torque should be calculated for each mill run of casing based on number of turns past hand tight.
2. Connection make speed should not exceed 25rpm to prevent galling
3. Makeup should observe both torque gauge and thread vanish point
4. Torque values provided are under normal conditions and assume the coupling is flush with the thread vanish point or within two thread turns, plus or minus.
5. If the thread vanish point is buried two thread and 75% of torque is not reached the joint should be treated as a questionable joint.
6. If several threads remain exposed when recommended torque is reached apply additional torque up to 125% of recommended value. If more than three thread tunrs are left after 125% torque joint is considered questionable.

Joints 4-1/2 to 7 should be made up at least three turns past hand tight.

For the grades you listed this spec only has LT&C recommended torque.
Size Weight Grade ft-lb N • m
4.5 11.6 L80 2230 3030
4.5 13.5 L80 2710 3670
4.5 11.6 P110 3020 4100
4.5 13.5 P110 3660 4960
4.5 15.1 P110 4400 5960

5.5 17.0 L80 3410 4630
5.5 20.0 L80 4200 5700
5.5 23.0 L80 4930 6690
5.5 17.0 P110 4620 6270
5.5 20.0 P110 5690 7720
5.5 23.0 P110 6680 9060

 

[johnchrc]

Good specific replies. I'm guessing you are a VAM employee or in the Premium Threading business. Where does this information come from? I can't just take your word for it even though I believe the information is correct.

When you say LTC should be made at least three turns past hand tight. Is that to obtain seal for internal pressure testing?

We now follow thread vendor spec regarding pipe dope.

We aren't using a rotary shouldered connection? Buttress. Some type of thread grease should be used on rotary shouldered. I see API used on drill pipe all the time, just not shoulder.

I meant ultra SF not STC for failed joint.

Is it not taboo to put PTFE tape on API connections to get a seal without having to apply much torque. Can it not cause connection to gall when you back-off and tape unwinds not to mention possibility of unzippering thread depending on amount. I think our shop and their management OK this practice so they don't damage Bullplug threads.



- CJ

 

[VAWTEng]

Yeah i should have clarified. What i meant on the RSC note was that API RSC dope is not the same as casing dope. But if your shop doesn't even work with RSC at all then it's probably a non-issue. Just wanted to mention that getting those crossed would case some issues.

Information above is straight out of RP5C1 1999.

I do not have any experience with PTFE on casing threads nor experience with bullplugs.

The best plan of action would be purchase a copy of RP5C1 & Bulletin 5A2