Case Study: STRESS SAVER® 3522 Hydrogen Production


Hydrogen Production


Temperature: Ambient
Application: 150# raised face HDPE flange adapters with reinforced nonmetallic backer flanges
Media: Nitrogen and plant air
Pressure: 104 psig (operating) 275 psig (test pressure)


Garlock was contacted by an engineering and construction firm responsible for the design and build of a new green hydrogen production facility in the southeastern USA. The service was HDPE (high-density polyethylene) piping and flange connections used for nitrogen and plant air systems.


The brand of HDPE piping chosen for the system utilized HDPE flange adapters fused to the ends of the pipes with reinforced non-metallic backer flanges, which created raised face-sealing surfaces. Analysis revealed that the recommended torque from the pipe flange manufacturer for ½” through 4”-150# flange sizes generated gasket assembly stresses from 929 psi to 3758 psi. The resulting stresses in several of the flange sizes were too high for traditional elastomeric gasket materials and could potentially lead to the gaskets being crushed. The customer was also concerned about the longevity of the gaskets in service with regard to aging, load retention, and long-term sealability. In addition, HDPE flange adapters tend to relax over time and contribute to load loss concerns.


1”-150# and 2”-150# flange test fixtures were produced by the pipe manufacturer and sent to Garlock for product testing and validation. Testing demonstrated that the STRESS SAVER® 3522 could seal nitrogen gas at the requested bolt load range. Additionally, the molded raised rib features of the gasket recovered nearly 100% upon removal from the test flanges. The test results gave the customer added confidence that the product would not only seal with ease but also had an excellent recovery to maintain the initial bolt load and offset any unpredictable relaxation and load loss that typically occurs with HDPE flange adapters. Also, the STRESS SAVER® 3522, being 100% PTFE, would not age or degrade over time.