ASTM A335 P91 Large Diameter Boiler Pipe
Seamless Grade P91 chrome-moly alloy steel pipe for elevated-temperature service in refining furnaces and supercritical boilers, with 508 mm OD. It provides excellent creep resistance for high-pressure feedwater heaters. Falls under 7304.59.20.80 as other alloy steel seamless tubes over 406.4 mm OD suitable for boilers and refining furnaces.
Import Duty Rates by Country of Origin
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If outside diameter ≤406.4 mm
Size threshold determines subheading; tubes 114.3mm ≤ OD ≤406.4mm go to 7304.51, while larger ones are 7304.59.
If of iron or non-alloy steel
Non-alloy steel versions classify under 7304.29; alloy steel requires minimum specified elements like Cr/Mo exceeding non-alloy limits.
If imported pre-assembled into heat exchanger
When supplied as complete heat exchanger parts rather than standalone tubes, may classify as machinery parts under Chapter 84.
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Import Tips & Compliance
• Provide hydrotest and nondestructive electric test (NDT) certificates as required for P91 grade to prove pressure integrity
• Declare exact alloy elements (9% Cr, 1% Mo) in entry docs; mismatches lead to duty reassessment or penalties
• Avoid bundling with fittings; ship as individual lengths to prevent set classification under 7307 or 7308
Related Products under HTS 7304.59.20.80
SA-213 TP347H Seamless Boiler Tube
Seamless tube made from TP347H stabilized austenitic stainless steel alloy, designed for high-temperature service in superheaters and boilers. It has an outside diameter of 457 mm, exceeding 406.4 mm, and meets ASME SA-213 specifications for pressure parts in power generation boilers. Classified under 7304.59.20.80 due to its seamless construction, alloy steel composition, circular cross-section, and suitability for boilers with large OD.
SA-213 T92 Superheater Tube
High-strength T92 martensitic alloy steel seamless tube for superheaters in ultra-supercritical boilers, featuring 432 mm OD. Optimized for temperatures above 600°C with superior oxidation resistance. Classified in 7304.59.20.80 for its large diameter, seamless alloy steel construction suited for superheaters.
P5 Alloy Seamless Refining Furnace Tube
ASTM A335 P5 (5Cr-0.5Mo) seamless tube, 419 mm OD, for transfer lines in petroleum refining furnaces. Withstands carburizing atmospheres at 650°C. HTS 7304.59.20.80 covers its alloy steel seamless design for refining furnaces exceeding 406.4 mm OD.
Grade 91 Condenser Repair Tube 16.5" OD
Replacement seamless P91 tube, 419.1 mm OD, for condenser water boxes in fossil fuel plants. Enhanced weldability for field repairs. 7304.59.20.80 due to large OD, alloy composition, and condenser suitability.
Alloy Steel Feedwater Heater Tube 18" OD
Seamless 457.2 mm (18-inch) OD tube from 2.25Cr-1Mo alloy steel for feedwater heaters in steam cycles. Corrosion-resistant U-bend configuration for heat exchange efficiency. Under 7304.59.20.80 as large-diameter seamless alloy tube explicitly for feedwater heaters.