How to Specify Industrial Piping Packages: A Procurement Engineer's Walkthrough

Coordinating pipes, flanges, fittings, valves, and gaskets into one traceable supply package

Industrial buyers rarely order a single product. A typical refinery, power plant, or marine vessel requires hundreds of line items, all of which must arrive in the correct grade, dimension, and certification. When the package is misaligned, the consequences are familiar: gaskets that don't seat, pipe flanges drilled to a different pressure class, and valves that fail hydrotest. This walkthrough explains how a single manufacturer can hold the whole package together, and why the choice of supplier matters as much as the choice of standard.

1. Start with the service envelope, not the part number

Before any procurement document is opened, the operating envelope has to be fixed. Three numbers drive almost every downstream decision:

• Design temperature – Determines whether carbon steel, low-alloy, or austenitic stainless is acceptable. ASTM A106/A53 covers the medium range; A335 P11/P22 is used above 540 °C; A312 TP304H/TP316H carries high-temperature boiler duty.
• Design pressure and class – Drives flange rating (Class 150, 300, 600…) and the matching bolt specification for the gasket stud bolt nut assembly.
• Fluid corrosivity – Seawater, sour service, and chloride-bearing process streams push the spec toward copper-nickel, super duplex, or lined systems.

Locking these three numbers first prevents the classic mistake of sourcing a 150# flange to mate with a 300# valve. It also keeps the bolt load, gasket stress, and flange facing geometry in agreement across the joint.

2. Match the pipe to the service

For high-pressure process and steam service, stainless steel pipe per ASTM A312/A312M is the most common pick, with TP304/L for general chemistry and TP316/L for chloride exposure. Boiler and superheater lines often shift to TP304H/TP316H, where the higher carbon content gives better creep resistance at sustained high temperature. For lower pressure or structural service, ASTM A53 welded pipe remains the workhorse, and API 5L PSL1/PSL2 covers oil and gas transmission.

A complete pipe specification on a purchase order should at minimum include:

• Standard and grade (e.g. ASTM A312 TP316L)
• Manufacturing route (seamless / welded / cold-worked)
• Nominal pipe size and schedule (1/2" Sch 40S, 6" Sch 40, etc.)
• Length type (single random, double random, cut-to-length)
• End finish (plain end, bevelled, threaded)
• Required testing (hydrotest, eddy current, ultrasonic, PMI)
• Documentation (MTC to EN 10204 3.1, NACE MR0175 if sour)

3. ｓｅｌｅｃｔ flanges that match the pipe and the pressure class

Flanges are the visible interface of a piping system, and they are the most common source of leakage when the package is mis-specified. Three parameters must align: the pressure class, the facing type, and the material.

Pressure class and facing

ASME B16.5 governs Class 150 through Class 2500 flanges up to NPS 24. For larger diameters, ASME B16.47 Series A or B applies. Facing choice is equally important: raised face (RF) is the default; flat face (FF) is used for cast iron or non-metallic flanges; ring-type joint (RTJ) handles high-temperature, high-pressure hydrocarbon service; tongue-and-groove (T&G) and male-and-female (M&F) suit small-bore, frequent-maintenance systems.

Material family

Steel flanges are usually ASTM A105 for carbon steel, A350 LF2 for low-temperature, A182 F304/F316 for stainless, and A182 F11/F22 for alloy. The steel flanges for marine and offshore work often follow EEMUA, BS, or DIN in parallel. For seawater service, copper-nickel flanges (90/10 or 70/30) per EEMUA 234 and ASTM B466 are the proven choice because of their resistance to biofouling and impingement attack.

4. Coordinate fittings, gaskets, and bolting as one system

A flange joint is a system, not a part. The gasket, studs, and nuts must be matched to the flange class, facing, and fluid. A typical industrial package therefore includes:

• Soft cut gaskets – spiral-wound with graphite or PTFE filler, used with RF facings; or compressed non-asbestos for utility water.
• Ring-joint gaskets – oval or octagonal, paired with RTJ flanges in refinery and high-pressure steam.
• Stud bolts and nuts – ASTM A193 B7 / A194 2H for standard service; B8 / 8M for stainless; B16 / B8M for high-temperature alloy service.

Mixing classes on the same joint is the most frequent cause of joint failure. A practical rule: if a flange is rated Class 300, the bolts must be at least B7, the gasket must be spiral-wound or RTJ, and the torque must be calculated for the actual gasket stress.

5. Treat valves as a separate engineering stream

Industrial valves are the items most often re-specified late in the project. Function determines the type: gate valves for full-bore isolation, globe valves for throttling, ball valves for quick shut-off, check valves to prevent backflow, butterfly valves for large-diameter utility lines, and plug valves for slurries or frequent cycling. Each of those types is itself a sub-engineering exercise, with body material, trim, seat, and actuator selected to the service.

For project procurement, valves are usually released in a separate requisition and joined with the piping package only after their face-to-face dimensions are confirmed against the flanges. This avoids the common rework of mating a valve with a different flange standard or pressure class than the adjacent pipe.

6. Why a single-source integrated supplier reduces project risk

The technical sections above make one thing clear: an industrial piping package is interconnected. When pipe, fittings, flanges, gaskets, bolts, and valves are sourced from five different vendors, traceability and accountability fragment. A single integrated supplier that produces the pipe, the fittings, and the flanges under one quality system, and that holds inventory of the bolting and gaskets, can deliver the whole bundle in matched heat numbers and dimensions. That reduces documentation workload, simplifies inspection, and shortens the site storage and assembly window.