The COMPRESS Rating Mode takes your pressure vessel or heat exchanger and determines its MAWP, MAEP and MDMT. Rating Mode is often used when performing post construction calculations such as de-rating in-service pressure vessels and heat exchangers. Some pressure vessel designers like to use it to input different pressure / temperature combinations and let COMPRESS tell them where the ASME® Code errors are. COMPRESS also offers a true Design Mode where you input design data and COMPRESS selects component thicknesses, sizes, placements and optionally also determines MAWP, MAEP and MDMT. You can switch between Rating and Design Modes in COMPRESS at any time.