Stainless Steel Pipe Plug And Bushing Size

Stainless steel pipe plugs and bushings play roles in ensuring secure and leak-proof connections.

A pipe plug is a threaded fitting used to seal the end of a pipe or fitting, preventing fluid leakage and protecting internal threads from contaminants. Common types include square head, hex head, and round head plugs, each offering distinct advantages in installation and removal.

Bushings, on the other hand, serve as reducers, connecting pipes or fittings of different diameters while maintaining system integrity. Typically featuring a hexagonal head for easy wrenching, bushings allow for seamless transitions in pipe sizes, reducing turbulence and pressure drops.

This article summaries stainless steel pipe plugs and bushings by size, outlining the standards, critical dimensions, and specification.

Standards and Specifications

The design and manufacturing of stainless steel pipe plugs and bushings are governed by ASME B16.11. This specification outlines pressure-temperature ratings, tolerances, markings, and material requirements, applicable to sizes from 1/8" to 4" nominal pipe size (NPS).

Plugs and bushings are not classified by pressure classes like other fittings but are rated for use up to Class 6000, depending on material and application.

Tolerances ensure tight fits: for example, thread dimensions follow ASME B1.20.1 for NPT threads, promoting secure sealing without galling.

Our factory employs advanced forging techniques and non-destructive testing to exceed these standards, resulting in fittings with minimal defects and extended service life.

Dimensions of Stainless Steel Pipe Plugs

Pipe plugs are available in various head styles to suit different torque requirements and space constraints. Dimensions are specified in millimeters per ASME B16.11, with NPS ranging from 1/8" to 4".

Square Head Plugs

Square head plugs offer a robust grip for high-torque applications, ideal for manual or powered tools. The square head plug prevents slippage, ensuring a tight seal.

NPS	DN	Width Flats (B) Min	Length (E) Min	Height Square (C) Min
1/2"	15	14	14	10
3/4"	20	16	16	11
1"	25	21	19	13
1-1/4"	32	24	21	14
1-1/2"	40	28	21	16
2"	50	32	22	18
2-1/2"	65	36	27	19
3"	80	41	28	21
4"	100	65	32	25

Hex Head Plugs

Hex head plugs are preferred for their compatibility with normal wrenches, facilitating quick installation in small spaces. They provide balanced torque distribution.

NPS	DN	Minimum Length (E)	Minimum Hex Height (J)	Nominal Width Flats (F)
1/2"	15	14	8	22
3/4"	20	16	10	27
1"	25	19	10	35
1-1/4"	32	21	14	44.5
1-1/2"	40	21	16	51
2"	50	22	18	63.5
2-1/2"	65	27	19	76
3"	80	28	21	89
4"	100	32	25	117.5

The hex height allows for secure gripping, while the width across flats scales with size to handle increasing torque. A 2" NPS hex plug, with its 63.5 mm nominal flat width.

Round Head Plugs

Round head plugs feature a cylindrical head for flush installations where low profiles are priorities, though they require specialized tools for removal.

NPS	DN	Length (E) Min	Length (A) Min	Diameter Round Head (D)
1/2"	15	14	44	21
3/4"	20	16	44	27
1"	25	19	51	33
1-1/4"	32	21	51	43
1-1/2"	40	21	51	48
2"	50	22	64	60
2-1/2"	65	27	70	73
3"	80	28	70	89
4"	100	32	76	114

The round diameter ensures a smooth exterior, reducing snag risks in exposed applications. For larger sizes like 4" NPS, the 114 mm head diameter provides ample sealing surface.

Our stainless steel plugs resist deformation under pressure, offering value through reduced maintenance needs.

Dimensions of Stainless Steel Bushings

Bushings enable size reduction in threaded connections, with external male threads and internal female threads. Hexagonal heads dominate for wrench-friendliness.

Hexagon Head Bushings

These bushings combine reduction functionality with easy adjustability, suitable for one or multiple size steps.

NPS	DN	Length (A) Min	Height Square (B) Min	Width Flats (C) Min	Nominal Head Diameter (D)	Length (E) Min	Hex Height Bushing (G)	Hex Height Plug (H)
1/8"	6	10	6	7	10	35	6	-
1/4"	8	11	6	10	14	41	16	3
3/8"	10	13	8	11	18	41	18	4
1/2"	15	14	10	14	21	44	22	5
3/4"	20	16	11	16	27	44	27	6
1"	25	19	13	21	33	51	36	6
1-1/4"	32	21	14	24	43	51	46	7
1-1/2"	40	21	16	28	48	51	50	8
2"	50	22	18	32	60	64	65	9
2-1/2"	65	27	19	36	73	70	75	10
3"	80	28	21	41	89	70	90	10
4"	100	32	25	65	114	76	115	13

Threaded Flush Bushing

Flush bushing, also known as a face bushing or insert bushing, features male external threads and female internal threads, allowing it to connect pipes or fittings of differing diameters.

DN	Nom. Pipe Size	Length A (Min)	Height of Square B (Min)	Width Flat C (Min)	Nominal Diameter of Head D (Nom)	Length E (Min)	Width Flat F (Nom)	Hex Height G (Bushing) (Min)	Hex Height H (Plug) (Min)
6	1/8"	10	6	7	10	14	35	16	3
8	1/4"	11	6	10	14	21	41	18	4
10	3/8"	13	8	11	18	27	41	22	5
15	1/2"	14	10	14	21	33	44	27	6
20	3/4"	16	11	16	27	36	44	46	7
25	1"	19	13	21	33	50	51	50	8
32	1-1/4"	21	14	24	43	65	51	65	9
40	1-1/2"	21	16	28	48	75	64	75	10
50	2"	22	18	32	60	90	70	90	11
65	2-1/2"	27	19	36	73	115	70	115	12
80	3"	28	21	41	89	115	76	115	13
100	4"	32	25	65	114	115	76	115	14

Stainless Steel Pipe Plug and Bushing Procurement

Define the Connection: Determine the exact thread standard and NPS of the port you are sealing (for a plug) or connecting between (for a bushing).

Select the Pressure Class: Match the class to the your pressure-temperature requirements. Class 3000 is the most common general service grade. Class 6000 is for severe service.

Specify the Material Grade: Clearly state the ASTM material standard (e.g., A182 F316/F316L for 316 Stainless, A182 F51 for Duplex 2205). For plugs, also specify the head style (hex, square, socket).

Consider the Application:

Sanitary/Food Grade: Specify 316L, electropolished finish, with no cavities. Socket head plugs are often preferred.

Subsea/Chemical: Specify high-grade alloys (Alloy 625, Duplex), often with a tested, traceable hydrostatic pressure rating.

Temporary/Test Applications: Consider pneumatic test plugs with sealing rings rather than standard threaded plugs.

Contact us today for quote.