In geothermal fields the material is driven less by pressure than by fluid chemistry. Chloride, carbon dioxide and hydrogen sulphide, combined with pH and temperature, shorten the life of carbon steel. Production, steam, separator outlet and reinjection lines each need a different material class. We select the right item together with you, based on the well analysis.
Chemistry varies from well to well even within the same field. Common situations:
| Condition | Risk | Common answer |
|---|---|---|
| High chloride | Pitting and stress corrosion cracking | Duplex 2205, super duplex; 316L limited |
| CO2 dominant, low chloride | General thinning | Carbon steel with corrosion allowance, inhibitor |
| H2S present | Sulphide stress cracking | NACE MR0175 / ISO 15156 compliant material |
| Scaling (silica, calcite) | Loss of bore | Cleanable line design, full bore valves |
A precise selection requires the wellhead analysis and the operating temperature.
Buried sections of geothermal pipelines are cathodically protected. For the protection to work, the line must be electrically separated, which means an isolation gasket set at the flanged joint. The set includes the gasket body, stud sleeves and washers; if one part is missing, the isolation does not work.
Is 316L stainless enough for geothermal lines?
It depends on chloride level and temperature. In hot, high chloride fluid 316L is open to stress corrosion cracking; duplex 2205 or super duplex grades are preferred in those conditions.
Which material is used on reinjection lines?
Because chloride concentrates in reinjected water, duplex stainless, lined carbon steel or composite solutions come forward. The decision follows water analysis and operating temperature.
What does an isolation gasket set include?
An insulating gasket body, sleeves that separate the studs from the flange holes, and insulating washers. If any part is missing, electrical separation is not achieved.
Share your item list, isometrics or MTO file for your geothermal requirement; we reply with price and lead time the same day.