One of our drill stems broke this weekend. It’s a five piece threaded assy., four 20 ft. sections and one shorter section. It broke right at the threads at the top section. What kind of problems are you having?

We have had our share of issues with threaded drill stems, we also have a coker set which still uses hexagonal single piece drill stems which have thier own unique issues. Largely the threaded stems are trouble free if you pay attention to them and perform periodic inspection of the joint transitions. We also utilize a number of interlocks which reduce the shock loading on the assemblies, and are currently looking at the autoswitching tools which has been successful in elliminating strain on the stem due to coke falls. We also have to continually slow turn our rotary joints as they freeze up when the temperatures approach -40C. I’d be most willing to share any insites you have on the topic.

Further to kosment’s response, we have experienced corrosion on the threaded connection that leads to leaks. The connections have seized when we attempt to unthread them. Has anyone experienced a drill stem free fall due to failure of a corroded, threaded joint?
 
 

Can anyone provide information on the reliability of and a supplier of drill stem freefall arrest systems for coking operations?

the company with a lot of  design is Flowserve(the old company Pacific), although at the moment the other company Ruhrpumpen (Germany ) has installed some new systems, I  have had in operation both design, that comparativily the Ruhrpumpen, is a robust system, also this system is  less prone or submissive to failures as much in the   rotary joint, since, since they are used  gears box instead of bearing, and the free fall arrestor have better realbility and security than the flowserve. his it is my point of view after to have operated with both systems
Im sorry for my english, If you need more information let me know
 

Drill stems provided by Flowserve on recent projects have a swaged end that has a larger outside diameter on the female threaded end, compared to older designs. This improves the integrity of the threaded joint.
 
I agree that you need to inspect & maintain your drill stem regularly. Use the proper lube and tools when tightening the joints, and don’t ram the coke bed.
 
CG

The Flowserve fall arrest system utilizes two modified Block Stop (Suppliers name) fall arrestors which work quite well when new. Care must be taken to ensure the linkages are inspected and adjusted to grip their respective cables at the same reaction height as they do wear or premature failure will occur. ( We have seen a couple malfunction due to this issue) The Ruhrpumpen mechanism is a far more robust system as mentioned, and is my overall preference, but both work as designed if they are properly maintained. We did have to make some modifications so that the Flowserve system components so that they could adequately be adjusted and maintained.

can you tell us what modifications were made, to the flowserve system. what were the reasons for failures?

Scorpion Oil Tools

I had the pleasure of visiting a plant in Martinez, CA that had a similar problem. We demonstrated our Scorpion 800 Hydraulic Tong. This safe, high torque tong was able to break-out some frozen joints with great ease. It also makes-up joints to exact torque specs without the error in the feeler gauge. Please feel free to contact me email pauls@scorpion.cc