Claxton recently provided a sub-sea hot tapping solution in the Brent field, including a machine rated for 10,000psi safe working pressure.
The Problem
There was a high risk of a hydrate build up and potential pressure up to 140 BAR from tree valves which were suspected to be leaking. The hot tap operation would enable the pressure to be vented and circulated from the flowlines.
The Solution
Claxton supplied a set of hot tapping tools specifically tailored to the system and environment in question. The hot tap operation was to drill at a water depth of 140 metres into 8” OD Flowlines which were a Duplex 23% CR material and 10” OD Flowlines which were a carbon steel grade X-65 material. The flowlines had a protective polyurethane coating which was removed prior to the drilling operation.
The Operation was Diver assisted for rig up purposes, then operated remotely via an umbilical returning to a surface control package
The Result
Claxton delivered our unique design soft seal (no-weld) saddle clamp for the duty of interfacing the hot tap system to the flowline. This low impact method of interface has the added advantage of a dual seal gallery built into the clamp, providing the ability for injection of a liquid plastic sealant should it be required which ensures interface integrity. Although this facility was not required in this application, this is a beneficial feature as the condition of the surface of subsea flowlines and tubulars is often unknown.
Total Drilling time per flow line was 25-30 minutes. The operation comprised of 5 hot taps, all completed safely and successfully.
For more information about hot tapping from Claxton, and a video of a subsea hot-tap in action click here>