Surface Finishing for Hydrogen and Electrolyzer Components

The short answer: Hydrogen systems put stainless and nickel-alloy surfaces under two stresses at once. On the hydrogen side, hydrogen embrittlement and permeation make smooth, defect-free, passive surfaces a design requirement for piping, valves, separators and bipolar-plate hardware. On the oxygen side of an electrolyzer — and in any oxygen-enriched stream — components must be cleaned for oxygen service to CGA G-4.1 and ASTM G93 exactly as they would be in an air separation plant. Harrison provides electropolishing, passivation and oxygen-service cleaning from Houston, inside the Gulf Coast hydrogen hub that stretches from Houston's electrolyzer manufacturing and pipeline network to Corpus Christi.

Components and where each process applies

Electrolyzer stack and balance-of-plant hardware. Stainless end plates, separators, flow-field and bipolar-plate components, frames and manifolds are electropolished to remove the smeared, stressed surface layer from machining and leave a bright, chromium-enriched surface with fewer crevices. Oxygen-side components are oxygen-cleaned after finishing.

Hydrogen piping, valves and fittings. Passivated to ASTM A967 or AMS 2700 after welding or machining to remove free iron; electropolished to ASTM B912 where a low-Ra, low-particle wetted surface is specified for high-pressure or high-purity hydrogen.

Compression, storage and fueling hardware. Valves, regulators, dispensers and tube trailers in stainless and nickel alloys are passivated and precision cleaned; oxygen-enriched purge and blending hardware is oxygen-cleaned.

Fuel-cell and turbine gas trains for backup power and distributed generation are cleaned to the same practice used for industrial gas; see oxygen cleaning.

Specifications

ASTM A967 and A380 (passivation and cleaning of stainless) · AMS 2700 · ASTM B912 (electropolishing) · ASME BPE surface-finish designations where borrowed for wetted-surface Ra · CGA G-4.1 and ASTM G93 (oxygen service cleanliness) · owner and OEM specifications supplied with the order. Electropolishing typically reduces Ra by 30–50% from the starting finish; see how to specify electropolishing for drawing callouts and material-removal allowances.

Capacity and documentation

Harrison's 25,000 sq ft Houston facility has four electropolishing lines, nitric and citric passivation, oxygen cleaning with a Class 1000 cleanroom for packaging, four overhead cranes and 15,000 lb material handling. Every job ships with a certificate of conformance naming the standard and method, Ra reports for electropolished surfaces where specified, passivation verification per ASTM A967 where specified, and lot traceability. The quality system is registered to ISO 9001:2015 and ISO 14001:2015.

Representative project

A hydrogen equipment manufacturer building a pilot electrolyzer line needed a set of stainless manifolds, separators and oxygen-side piping components finished before stack assembly. Harrison electropolished the wetted surfaces to the Ra target on the drawings, passivated the remaining stainless hardware to ASTM A967, oxygen-cleaned and verified the oxygen-side components to the specified ASTM G93 level, and packaged everything in the cleanroom, bagged and labeled by assembly, with a certificate of conformance and Ra reports per line item.

Request a hydrogen component quote

Send the drawing, alloy, quantity, the specification and which side of the system the components serve. We'll quote within one business day; expedited service is available and lead times vary with shop load.

Request a Quote · Call 800-245-5707