Ball valve repair case study

Paul Boughton

Pentair Valves & Controls has successfully provided maintenance support under its specialist service brand, SABO, for a valve repair project at one of the largest gas storage facilities in Europe. After experiencing leakage of ball valves in the facility, the customer turned to Pentair to discover the reason for the loss of seal tightness and provide maintenance to solve the issue within a short timescale.

A chosen partner based on the team’s expert capabilities in this area, Pentair exceeded expectations and completed the job almost two weeks ahead of schedule. This minimised downtime and loss of production for the 17 billion cubic meter gas storage facility. On examination of the critical ball valve, Pentair discovered corrosion of the seat and inner valve body, and identified that the seat required reworking and a hard-facing. By promptly determining the root of the problem, providing a mirror polished surface to the ball and adjusting the clearance with new o-rings, Pentair delivered a successful outcome. This fast service completion also led to the early start of the pipeline testing procedure, which in turn allowed for early restart of the full pipeline. 

The 30 inch / 750 CL 600 ball valves were located between the depleted gas reservoir used as storage 2,500m underground at the facility, and the pipeline system. Featuring an actuator with a high integrity pressure protection system (HIPPS) function, the valves isolate the high pressure gas storage from the pipeline system. It was paramount that Pentair delivered a successful and rapid outcome in order for the customer to fulfil their critical requirement of injecting gas into storage tanks by a fixed deadline. 

The repair project posed a number of challenges for Pentair to manage, including handling due to the weight of the valves of more than 15 tons when assembled with the actuator. The extremely hard surface of the outer valve body also proved problematic. To overcome this, the previous coating, a two component polyurethane specific to offshore pipelines, was removed and grid blasted, which required special cast steel splitters - a unique capability for valves of this size. The Pentair team worked continuously to complete the mirror polishing of the valve ball, which helped to ensure the early completion of the valve service.

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