Multiport Ball Valve Solution for Well Injection of Corrosion Inhibitor

An offshore gas production platform in Trinidad & Tobago had an application using multiport ball valves for well injection of corrosion inhibitor. The application called for ten (10) class 2500 trunnion mounted 3-way ball valves in super duplex body and Inconel trim materials. The valves required fire testing to API 607 as well as fugitive emissions testing to ISO 15848. A T-Port ball is required for two position operation.

During testing onsite in Trinidad, the valves in the Position #1 configuration were leaking to the recycle port once the inlet port was pressurized to around 200-250 psi. This did not allow them to reach the needed 1500 psi to properly inject the wells. With first gas production approaching within weeks they needed an urgent solution.

By Chance Russo, Director of Sales & Valve Products – Max-Air Technology/Sesto Valves

In Position #1 the corrosion inhibitor is pressurized up to 1500 psi and goes straight through from the inlet to the outlet. The ball is also open to the blank port and the recycle port holds back a residual pressure of < 100 psi.

In Position #2 a 90-degree clockwise turn keeps the ball open to the inlet, blank, and recycle ports at a pressure less than 100 psi, while the outlet port holds back a pressure around 1500 psi. This pressure must not leak by or be allowed to communicate to the inlet and recycle ports.

The Problem

The valves in the Position #1 configuration were leaking to the recycle port once the inlet port was pressurized to roughly 200-250 psi. This did not allow them to reach the needed 1500 psi to properly inject the wells.

Issues like this are common among multiport ball valves as there are currently no international or industry design standards. No widely accepted testing protocols, procedures, or recommended practices exist either.

The Solution

Sesto Valves was invited to review the design and application. Upon review of the application, it became apparent that the valves installed only had three seats in their design. A T-Port ball in this application type required a fourth seat at the blank port in order to seal properly in all positions. In order to prove the hypothesis that a fourth seat was requires, a witnessed proof of design test was performed for the end user.

Proof of Design Testing

An elaborate test arrangement was devised to test the three ported seats in three flow positions in both low and high pressures. Flow Position A was the recycle position, with the outlet port pressurized to ensure that the flow did not leak back to the inlet or recycle ports. Flow Position B was tested by pressurizing the inlet to prove that no flow would leak to the recycle port as did the valves currently installed. This was the most important test and the differentiator in proving that the alternate design would be appropriate. Flow Position C was the recycle position the inlet port pressurized to ensure there was no leakage to either the outlet or recycle ports. There were six seat leakage tests that took place; each test was conducted for a 5-minute duration. A shell test at 1.5 times max pressure for an unprecedented duration of 30 minutes was also performed.

The Result

The test valve and all of the subsequent production valves were each witness tested with hydro in the manufacturing facility, and later retested with gas on site in Trinidad. The newly proposed valves passed all the testing and were delivered and installed to the project on time for first gas, only 6 weeks after first contact. Sesto Valves is the only manufacturer with a certified universal flow multiport design, which is also fire and fugitive emissions tested. This design ensures zero leakage and functionality in a number of flow scenarios, and it allows end users to save space and costs by eliminating redundant piping and valves.