Duplex stainless steels – Classification in four groups
The PREN (Pitting Resistance Equivalent Number) for duplex steels is an important parameter for classifying duplex steels also from the point of view of corrosion resistance, such as chloride stress corrosion cracking (SCC). Duplex materials have evolved in recent decades and are now classified into 4 groups: This classification is not officially standardised, but it […]
Is Design Approval by a notified body required under Modul G?
Module G does require that a notified body must examine the design of the pressure equipment and it is considered reasonable to expect the notified body to inform the manufacturer of the results of the examination. Module G does not contain any explicit requirement for approval of the design by the notified body. However, it […]
Which documents have to be available for the final inspection of a Pressure Equipment?
Pressure equipment shall undergo a final inspection to assess visually and by examination of the accompanying documents compliance with the requirements of this Directive. Test carried out during manufacture may be taken into account. As far as is necessary on safety grounds, the final inspection shall be carried out internally and externally on every part […]
Weldolet – Integral reinforced forged branch outlets
Weldolet fittings – the Branch Connection Fittings are also named as Outlet fittings. Outlets are a family of forged products used to make 90 degree or 45 degrees integrally reinforced branch connections from a header pipe or run pipe to an outlet pipe or branch pipe. When stress concentrations and cyclic loads are a concern, detailed analysis is required. […]
What means ISO 5208 leakage rate A?
The ISO 5208 rate A specify a leakage by internal tightness seat test (or often also called closure test) of valves. Usually 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 to atmosphere. ISO 5208 specifies valve closure tests of an […]
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, […]