The reason for choosing which construction code?
We are often asked by clients: “Which code do we have to choose for our equipment, ASME or the EN code ? And are we still conforming to PED regulations if we choose the ASME code, which is a United States code ?” We do understand that this can be quite confusing, so we wanted to write this article to offer some clarity in this matter.
First of all, what do we have to do to comply with PED ? This European guideline requires all pressure equipment to be designed appropriately, taking into account all relevant factors that will garantee the safe use of the equipment during its complete life cycle. This can be achieved by using a calculation method based on formulas,analysis, fracture mechanics or a combination of these. As a manufacturer we can then choose either to use the EN 13445, ASME VIII Div. 1, AD-2000 or other design codes.
Each code has its own specific emphasis on either strength calculations, welding controls, welder qualifications and other. Looking at our experiences, we see that both ASME and EN13445 are the most popular choices.
Analysing all differences between both codes in this article, would lead us too far astray (each code description needs close to 800 pages to be described…). Nevertheless we see a common thread through these codes: a balance is sought between the thickness of the materials and the level of the welding controls. In other words, the wall thickness of your pressure vessel will be less thick, as more welding
control is applied.
To conclude it should be clear that a balance must be sought between welding quality requirements and material thicknesses, since both have implications on the final manufacturing cost of the pressure vessel.