Melangkah 1: define the real design envelope

Record design pressure, suhu desain, operating range, upset conditions, process medium, tunjangan korosi, cyclic duty and expected service life. High-temperature selection is not a single-temperature exercise. Long-term creep exposure, thermal transients, oksidasi, hydrogen damage and corrosion under insulation may control different parts of the decision.

The adopted piping code, client specification and line class establish the allowable material route. Published marketing temperature ranges are not a substitute for the code’s allowable stress data or the flange standard’s pressure-temperature tables.

Melangkah 2: select a compatible material system

Match the flange to the adjoining pipe, perlengkapan, badan katup, weld metal and bolting strategy. F11, F22 and F91 each belong to a different metallurgical system. A flange with higher nominal strength can introduce mismatched welding, thermal expansion or heat-treatment requirements if used outside its intended line class.

Melangkah 3: rate the flange and design the joint

Use the applicable ASME standard and adopted edition to determine the pressure-temperature rating for the exact material group and class. Kelas 600 does not mean 600 psi, dan Kelas 900 does not mean 900 psi. Available pressure changes with material and temperature.

Then select flange type, menghadap, gasket and bolting as one joint. Weld neck flanges are commonly used for critical high-temperature lines because the butt-welded hub provides a gradual transition. The bore and weld preparation must match the ordered pipe wall. RF versus RTJ selection depends on the equipment connection, standar paking, service and project philosophy; the two facings are not field-interchangeable.

Melangkah 4: lock in fabrication and quality controls

Before manufacturing, define the required forging route, perlakuan panas, frekuensi pengujian, batas kekerasan, PMI coverage, surface examination, pemeriksaan ultrasonik, dimensional inspection and certificate type. The order should also state whether third-party inspection or hold points apply.

Untuk sistem yang dilas, align the flange grade with the qualified WPS, memanaskan lebih dulu, interpass controls, logam pengisi dan PWHT. Nilai 91 work deserves particular discipline because composition verification alone cannot confirm a correct microstructure. Complete traceability from raw material heat to final marking is essential for every grade.