The Pressure Equipment Directive (PED) is a European Legislation aimed at removing the technical barriers to trade relating to the supply of pressure equipment throughout Europe. The PED is based on Essential Safety Requirements (ESRs) that govern design, manufacturing, inspection and testing. PED affects most equipment that will be placed on the market in the European Economic Area (EEA) designed for pressures above 0.5 bar g or 7.25 psi g.
PED covers all types of fixed equipment, including:
1. Pressure Vessels
3. Steam Generators
4. Pressure Accessories
5. Safety Accessories
6. Assemblies comprising two or more items listed above
TPED 99/36/EC (Transportable Pressure Equipment Directive)
The TPED applies to most transportable pressure equipment within the EU. Unlike the PED, the TPED is not a New Approach Directive. Compliance with one of the officially mandated standards is needed.
ASME is the acronym for American Society of Mechanical Engineers. Founded in 1880, ASME is a professional organization focused on technical, education and research issues in the engineering and technology community. ASME develops and maintains internationally recognized industrial and manufacturing codes and standards that enhance public safety. In 1911, ASME formed a committee and it is currently responsible for establishing rules of safety governing the design, fabrication and inspection during construction of pressure vessels, and interpreting these rules when questions arise regarding their content.
Since 1916, ASME has accredited companies in the pressure vessel industry to certify that their products, services and quality system comply with the ASME Boiler and Pressure Vessel Code. The Symbol on a vessel is used to confirm the stamped item is in conformance to the latest edition of the Code.
Starting right with the design, there are rules that have to be followed. Parameters such as wall thicknesses, materials, flange ratings, welding details, and extent of nondestructive examination are determined by design conditions such as pressure, temperature, corrosion allowance, fluid running through the strainer, and any specific requests from the customer. Based on these conditions a comprehensive set of calculations are prepared. They are reviewed and approved by the ASME Inspector.
Once the design has been approved, the materials can be purchased. The materials used must comply with the Boiler and Pressure Vessel Code, in particular Section II Parts A through D. Material Test Reports are required for all materials. These reports include such things as chemical analysis, heat treatment performed (as applicable) and any NDE testing results. Review of the reports will determine if the material is in compliance with the Code requirements. The reports are supplied by the vendor with the material. All material must be clearly identified to trace it to the applicable Material Test Report. The ASME Inspector will check the material and review the Material Test Reports to ensure their conformity to the Code.
Before production can begin, the Inspector will verify that the welding procedure to be used has been qualified and the welders performing the welding are certified. This is in accordance with Section IX of the Code. At the same time, the Inspector will inform us of the extent of his inspection on the fabrication part of the job. Usually, he will want to see the strainer fit-up, that is the unit just before the welding is performed. The next step is to review the unit after fabrication is complete to ensure welding was performed to Code requirements. At the same time, the Inspector will review any non-destructive testing results. Then he will witness a hydrostatic test performed in accordance with the requirements of Section VIII Division 1. The final step is the application of the nameplate. This is also witnessed by the Inspector. The nameplate will be marked with relevant design conditions and the U or UM Code Symbol.