Can exessive grease influence the torque for threaded connections? 1

[johnchrc]

If too much grease is used on threaded connection (Stub Acme/O-Ring Connection), can this cause problems with connection?
Recently, I made-up a 6" SA Thread connection that had two O-Ring grooves in box. Seal land was located on nose of pin thread. Total connection length was quite long (~ 5-1/2 inches). Thread made up by hand initially but torque to rotate quickly increased (before o-ring seated) and eventually required ~ 6,000 ft-lbf torque to shoulder (way too high). No galling. Movement was smooth, just tight. Used high temp seal grease for threads and seals that have been using for years. In addition, I made up three more identical connections but applied much less grease, just enough to apply very light layer to threads and seal surface. Connections were much easier to make-up.
I have been warned in the past not to use too much grease and I try to comply and have never had problems (at least in recent memory). I could see how grease could build up and get trapped between threads as connection is made up. Also, pressure could increase on seals causing additional seal friction resisting rotation.
Is too much grease a valid concern?
What problems will result?
How do you know how much grease is adequate?

 

[eltooon]

Hi johnchrc, I work in a company which designs and manufactures premium connections. We always tell our end-users not to over-dope the connections.
Just as you've experienced, too much grease will increase torque.
The effect is more significant when PRM is high: the grease doesn't have enough time to move away. When excessive grease is trapped in between the threads, it may lead to problems such as increased hooped stress, compromised sealing, leak in a later stage for casing/tubing (excessive grease will eventually seep away and leaves gap behind), or even connection damage.
So we recommand a thin even layer of grease applied before make-up. All thread/seal surface should be covered but the thread form should remain clearly visible.
Hope this helps.

 

[johnchrc]

eltoon,

Do you have any documents that demonstrate proper grease application?

I take it you work for a company similar to Vallorec, Hydril, Hunting...

What is PRM?

In the future, I would place a weep hole in the box in addition to being less liberal with the grease. Because these are test fixtures, we usually receive them with no coating at all (except oil coat). We usually phosphate but I will not apply on connection with o-rings. Like to put Xylan or baked on dry moly coating with low friction factors and easy on the seals.

 

[eltooon]

johnchrc,

It should be RPM, sorry for the typo,

I work with Hunting. You can find our field running procedure documents online. Here's one example, it gives recommendations on how to apply thread compound(or grease):

http://www.hunting-intl.com/media/9357/apex-9.pdf

VAM and Tenaris Hydril has their guildlines too:

http://www.vamservices.com/Library/files/131_VAM_Book_Blue.pdf

http://www.tenaris.com/en/Products/PremiumConnections/TenarisHydrilRunningManual.aspx

Most of the premium connections comes with a weep hole on box to take the excessive dope. We call it a relief groove. Check out this:

http://www.hunting-intl.com/media/9366/ksl_apex_spr_prnt_6-04_red.pdf

"We usually phosphate but I will not apply on connection with o-rings."
Any reason why?