Project Case Study – Manufacture of BOP Testing Mandrels

In late 2017, Sharpe were approached by a drilling contractor to design and manufacture a mandrel sub to be used in the handling, pressure and function testing of their BOP stack. Sharpe designed and manufactured a range of mandrels to suit BOPs from 9” to 13 5/8” and tested with the following drill pipe sizes: 2-3/8”, 2-7/8”, 3-1/2” and 4-1/2”.

The mandrel and nubbin assembly is used to lower a pre-assembled BOP stack into position and safely nipple-up onto the wellhead spool / test stump. The mandrel is then utilised to test individual rams of the single and double gate BOPs.

Machined on the top of the mandrel is an NC50 box connection which is made-up to the pin connection of a Sharpe manufactured integral lift nubbin. Both the mandrel and the nubbin are engineered and certified for lifting to 30T WLL and a working pressure of 10,000psi.

The bottom disk of the mandrel has been tapped with a ½” NPT port to allow monitoring of the test pressure held at the sealing element during BOP pressure rating. This ensures the element is exposed to the test pressure. When testing from below, the disk is pushed into the base of the closed rams of the BOP.

Sharpe assist clients with custom tools regularly and have the ability to take a client’s concept design through detailed engineering and manufacture within a short lead time. The above mandrel will save the rig contractor critical hours in rig-up and BOP testing time and has been complimented by the associated operating company as evidence of continual improvement in rig efficiencies.


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