Research on Shah Denis Stage 2 started in 2011 when our customer entered the qualifying for 10″, 6″ and 2″ valves. Shah Deniz gas field is the largest natural gas field Azerbaijan. It is situated in the South Caspian Sea, off the coast of Azerbaijan, approximately 70 kilometers southeast of Baku, at a depth of 600 meters.

The field covers approximately 860 square kilometers. The Shah Deniz gas and condensate field was discovered in 1999. It is to bring gas into Europe without having to traverse countries like Russia or Iran, deemed to be politically unreliable
by some, with 40 trillion cubic feet – over 1 trillion cubic metres of gas in place.

Around $28 billion capital investment will be required to produce the gas and transport it to the Georgia-Turkey border. From there additional pipeline systems are planned to deliver 6 bcma of gas to Turkey and a further 10 bcma of gas to markets in Europe. Shah Deniz Stage 2, one of the largest gas developments in the world, will help increase energy, security of European markets through the opening of the new Southern Gas Corridor.

One of the main projects undertaken are for Shah Deniz are subsea valve compensators, during the development stages of the compensators our customer and Impress have dramatically increased the corrosion resistance of traditional compensators from 316 Stainless Steel to Alloy 625 which falls into the category of “super austenitic stainless steel”. Alloy 625 is a fully austenitic alloy offering excellent resistance to pitting and crevice corrosion.

Performance in these areas is often measured using Critical Pitting Temperatures (CPT), Critical Crevice Temperatures (CCT), and Pitting Resistance Equivalent Numbers (PREN).

The corrosion resistance of stainless steel is, basically, dependent on their chemical compositions. As a general rule, the higher the PREN, the better the resistance to pitting. However, alloys having similar values may differ considerably in actual service. Those with values greater than 38 on the PREN scale offer more corrosion resistance than the austenitic stainless steels. Alloy, with its PREN of 47, offers a cost-effective means of avoiding aggressive chloride attack. A number of tasks challenged our team including:

• Pre-production testing samples in 316L Stainless Steel
• Pre-production testing samples in Inconel Alloy 625
• The changes in manufacturing methods due to the tensile and yield strength of Alloy 625
• Welding Procedure Qualification testing
• Pressure testing
• The sourcing of raw material in the UK and USA