Carbon Steel Nipple — Factory Direct Supplier | Huaxia-Steel

A carbon steel nipple is a short length of pipe with male threads on both ends, used to connect two female-threaded fittings, valves, or equipment in a piping system. Despite their simple appearance, nipples are among the most commonly used pipe fittings in industrial, commercial, and residential piping — and their quality directly affects system integrity and leak-tightness.

Huaxia-Steel supplies carbon steel nipples manufactured from seamless or welded pipe conforming to ASTM A106, A53, and API 5L standards, in sizes from 1/8″ to 6″ (DN6 to DN150). We offer close nipples, standard nipples, and long nipples, all with precision-cut NPT, BSPT, or BSPP threads to ensure reliable connections in every application.

Product Overview

Carbon steel nipples are available in several configurations to suit different piping requirements:

• Close nipple (all-thread): Threaded for the entire length — the shortest possible connection between two female fittings. Typically used in tight spaces where fittings must be brought as close together as possible.
• Standard nipple (TBE — threaded both ends): Threaded at both ends with an unthreaded central section. The length is measured from end to end. Standard nipples provide flexibility in spacing between components.
• Long nipple (pipe nipple): Any nipple longer than 12″ (300mm). Available in cut lengths up to 72″ (1800mm). Used when valves, strainers, or other inline components need specific spacing.
• Hex nipple: A close nipple with a hexagonal section in the center, allowing wrench tightening. The hex provides a grip point without damaging the threads.
• Reducing nipple: Different thread sizes at each end (e.g., 1″ NPT × 3/4″ NPT) to connect pipes or fittings of different sizes.
• Swage nipple: A nipple with different end connections — one plain end for butt welding and one threaded end — used to transition from threaded to welded piping.

Specifications and Dimensions (Standard Nipples)

Nominal Size	OD (mm)	Wall Thickness (mm)	SCH 40	SCH 80	Standard Lengths
1/8″ (DN6)	10.3	1.73 / 2.41	SCH 40	SCH 80	Close, 50, 75, 100mm
1/4″ (DN8)	13.7	2.24 / 3.02	SCH 40	SCH 80	Close, 50, 75, 100mm
3/8″ (DN10)	17.1	2.31 / 3.20	SCH 40	SCH 80	Close, 50, 75, 100, 150mm
1/2″ (DN15)	21.3	2.77 / 3.73	SCH 40	SCH 80	Close, 50, 75, 100, 150mm
3/4″ (DN20)	26.7	2.87 / 3.91	SCH 40	SCH 80	Close, 50, 75, 100, 150, 200mm
1″ (DN25)	33.4	3.38 / 4.55	SCH 40	SCH 80	Close, 50, 75, 100, 150, 200, 300mm
1-1/4″ (DN32)	42.2	3.56 / 4.85	SCH 40	SCH 80	Close, 75, 100, 150, 200, 300mm
1-1/2″ (DN40)	48.3	3.68 / 5.08	SCH 40	SCH 80	Close, 75, 100, 150, 200, 300mm
2″ (DN50)	60.3	3.91 / 5.54	SCH 40	SCH 80	Close, 75, 100, 150, 200, 300mm
2-1/2″ (DN65)	73.0	5.16 / 7.01	SCH 40	SCH 80	Close, 100, 150, 200, 300mm
3″ (DN80)	88.9	5.49 / 7.62	SCH 40	SCH 80	Close, 100, 150, 200, 300mm
4″ (DN100)	114.3	6.02 / 8.56	SCH 40	SCH 80	Close, 100, 150, 200, 300, 450mm
6″ (DN150)	168.3	7.11 / 10.97	SCH 40	SCH 80	100, 150, 200, 300, 450, 600mm

Note: Standard lengths are typical stock items. Custom lengths available upon request. For nipples 4″ and above, SCH 40 is the most common wall thickness.

Available Material Grades and Pipe Specifications

Grade	Pipe Standard	Seamless / Welded	Max Service Temp
ASTM A106 Gr B	A106/A106M	Seamless	425°C
ASTM A53 Gr B	A53/A53M	Seamless or ERW	370°C
API 5L Gr B / X42	API 5L	Seamless or ERW	Per design code
ASTM A333 Gr 6	A333/A333M	Seamless	-45°C to 345°C
20# Steel	GB/T 8163	Seamless	400°C
Q235B	GB/T 3091	ERW	300°C

For most general industrial applications, ASTM A106 Gr B seamless nipples are the preferred choice due to their higher pressure rating and superior thread quality compared to ERW nipples. For low-pressure utility applications, A53 ERW nipples offer a cost-effective alternative.

Thread Standards and Specifications

Thread quality is the single most important quality factor for pipe nipples. A poorly cut thread will leak regardless of the sealant used. Our nipples conform to the following thread standards:

• NPT (National Pipe Taper): ANSI/ASME B1.20.1 — the most common thread standard globally. Tapered 1:16, providing a mechanical seal when tightened with thread sealant.
• BSPT (British Standard Pipe Taper): ISO 7-1 / BS 21 — tapered thread, widely used in Commonwealth countries, Middle East, and Southeast Asia.
• BSPP (British Standard Pipe Parallel): ISO 228-1 — parallel thread requiring a bonded seal or O-ring for leak-tightness. Used in hydraulic and instrumentation applications.

Thread inspection is performed using L1 (hand-tight) and L3 (wrench-tight) ring and plug gauges per the applicable standard. Threads are cut clean, free of burrs, and protected with light oil or anti-rust coating before packaging.

Applications

• Steam and condensate systems: Steam trap connections, drip legs, drain connections — A106 Gr B seamless nipples with SCH 80 wall thickness.
• Compressed air: Distribution headers, drop legs to tools and equipment — galvanized nipples preferred for corrosion resistance.
• Water and wastewater: Pump suction/discharge connections, chemical feed lines, sampling ports.
• Oil and gas: Instrument connections, vent and drain lines, chemical injection quills — often specified with NACE MR0175 compliance for sour service.
• Fire protection: Sprinkler branch lines, drain and test connections — UL/FM approved nipples required for listed systems.
• Natural gas: Residential and commercial gas piping — typically SCH 40 black nipples with NPT threads.
• HVAC: Chilled water, hot water, condenser water connections — SCH 40 black or galvanized.

Quality Assurance

• Raw pipe mill test certificate (MTC) verification per ASTM / API / GB standards
• Thread inspection: 100% gauging with L1 and L3 ring gauges for NPT; L1 and L2 for BSP
• Visual inspection for surface defects, thread damage, and rust
• Dimensional check: length, OD, wall thickness, thread length, bevel angle
• Optional hydrostatic testing (1.5× design pressure, minimum 5 seconds hold)
• Optional NDT: Magnetic particle testing of threaded ends for crack detection
• Galvanized nipples: zinc coating thickness per ASTM A153 Class B (minimum 45 μm)

Packaging and Shipping

• Threads protected with plastic thread protectors or wrapped in protective tape
• Packed in plywood cases, cartons, or pallets with waterproof wrapping
• Each nipple individually stamped or tagged with size, schedule, material, and heat number
• Galvanized nipples packed with separators to prevent zinc coating damage
• FCL container or LCL consolidation shipping available
• Port of loading: Tianjin, Shanghai, Ningbo
• Standard lead time: 1-2 weeks for stock items; 3-5 weeks for custom lengths or large quantities

Why Choose Huaxia-Steel?

• Precision threading: All threads machined on CNC threading machines with automatic gauging for consistent quality.
• Full traceability: Every nipple traceable to its pipe heat number, with mill test certificates provided.
• Competitive FOB pricing: Direct from factory — no distributor markup.
• Flexible MOQ: From small trial orders to full container loads.
• Surface finish options: Black (self-color), galvanized (hot-dip per ASTM A153), or painted.
• Custom labeling: Private label, color coding, or custom stamping available for volume orders.

Request a quotation now. Send us your nipple requirements — size, schedule, length, thread type, material, and quantity — and receive a detailed offer within one business day.