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| Proforma Safety, LLC Proforma PSI…when performance counts. Chloride Accumulation Blamed for Tubing Failures Although used for many years in offshore installations throughout the industry, 316 stainless steel now appears to have less corrosion resistance than earlier thought and may not be a suitable material for tubing in marine environments. Recent incidents have occurred on offshore platforms in the Gulf of Mexico and near Trinidad where external corrosion has led to failure of 316 stainless steel instrument and chemical tubing. Chloride is causing crevice and pitting corrosion, particularly where salt water has collected and evaporated, leaving a concentration of chlorides. The corrosion has predominantly occurred under the tubing retaining clips. Several companies have experienced this on their offshore installations. Based on testing performed by EPTG and review of field experience, the average life of 316 stainless steel with exposure to the outside environment in marine applications is approximately five years. EPTG has drafted a document, “Guidelines on Material Selection for High Reliability and NUI Facilities”, which provides a selection of materials which may be used to replace the 316 SS tubing including: Tungum, 254 SMO, Superduplex Stainless Steel and Alloy 625.
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