High temperature hydrogen attack (HTHA) of steels
Carbon steel process plant that operates with hydrogen at elevated pressure and temperature can be weakened by a phenomenon known as high temperature hydrogen attack (HTHA). The effect of hydrogen on carbon steel and its alloys has been known for some years, whereby at elevated temperatures and pressures, atomic hydrogen enters the microstructure of the steel, and reacts with […]
ISO 5208: Valve seat leakage rate
The internal tightness of valves is an essential safety requirement in pressurized systems. Leaks can be a danger to people and the environment or have an impact on processes. As there is no such thing as absolute tightness, technical tightness is defined by leakage rates. The necessary leakage rate must be determined by the operator […]
Valve seat test – What are Standards for leakage acceptance?
At the valve seat leakage test (also called closure test), one side (valve inlet) shall be subjected to the test pressure and amount of leak shall be measured on the opposite side of the valve. The seat leakage of control valve is the quantity of test fluid passing through an assembled valve in the closed […]
Pressure Relief Device: Standards and Specifications
Pressure-relieving valves and devices shall conform to the requirements specified standards and specifications. Additional requirements for certification and marking requirements such as PED (CE marking) and ASME BPVC (Designation stamp) should be apply. Below is a list of the most important standards and specifications: Standard/Specification Title Description Remark API STD 520 Part 1 Sizing, Selection, […]
Difference “Pressure Safety Valve” and “Pressure Relief Valve”
Understanding the differences between Pressure Safety Valves – PSV and Pressure Relief Valves – PSV is essential for selecting the appropriate device for a specific application. Pressure relieving devices include mechanisms such as Pressure Safety Valves (PSV) and Pressure Relief Valves (PRV), although there are other types of pressure relieving devices as well, such as […]
Qualification of line pipes for pressurised hydrogen applications?
Piping in acc. to ISO 3183 and API SPEC 5L must be evaluated with regard to their suitability for the use of hydrogen. Additional test procedures at qualifications of line pipes are required. Specifications and standards Specifications and standards for special hydrogen applications are currently only available to a limited extent and will become increasingly […]
Standards and specifications for steel materials in hydrogen systems
The infrastructure for hydrogen storage and transportation needs to be safely used for a carbon-neutral society. One of the most important issues for the integrity of a hydrogen system is material degradation caused by hydrogen. It is well understood that solute hydrogen in steel causes the degradation of material properties — so called hydrogen embrittlement.
Terms for hydrogen induced cracking processes of steels
The hydrogen induced cracking of steels takes place according to different processes. Both the environmental conditions and other influences such as stresses and the microstructure of the steels have an effect. In technical applications, a number of technical terms have become established for this, which are explained in the following table. Table with terms for […]
What are HIC resistant steels?
HIC-resistant steels are used when carbon steel is exposed to hydrogen sulphide (H2S) in the acidic or humid H2S environment of electrochemical corrosion reactions. HIC (Hydrogen Induced Cracking) is prevalent in wet H2S environments, which is often known as sour service. Therefore HIC resistant carbon steels are offered on the market so that these steels […]