8. BS flange standard

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Weld Neck Flanges (Code 111) – BS 4504

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Description

Weld Neck Flanges are flanges with a long neck welded directly to the pipe, which transfers pressure from the flange to the pipe, while minimizing pressure concentration at the connection. Its design includes a long neck that has the same inside diameter as the pipe, allowing for smooth and easy flow.

Applications

Weld Neck Flanges are commonly used in high pressure, high temperature systems or environments that require high safety and durability. Common applications include:

Oil and gas pipeline system
Chemical system
Electric Factory
Vending Machine
Pharmaceutical factory
Other industries requiring high durability and safety

Standards

BS 4504 is a British Standard that specifies the technical requirements for steel and alloy steel flanges for use in pipework systems. This standard covers:

Size : Size range according to BS 4504 is typically from DN 10 to DN 4000.
Working Pressure : Weld Neck Flanges according to BS 4504 can withstand a wide range of pressures, depending on the specific material and size.
Materials : Common materials include carbon steel, stainless steel, steel alloys and other high temperature resistant materials.
Flanges : Flanges can be machined flat, convex, or other contact faces depending on system requirements.

Weld Neck Flanges (Code 111) Dimensions and Thickness Table according to BS 4504

Size (Inches)	Outer diameter (OD) (mm)	Inside diameter (ID) (mm)	Neck Diameter (mm)	Flange Thickness (mm)	Bolt Circle Diameter (mm)	Number of Bolts	Bolt Diameter (mm)
1/2	90	15	21.3	11	60.3	4	12
3/4	100	20	26.7	13	69.9	4	12
1	110	25	33.4	15	79.4	4	12
1 1/2	125	40	48.3	16	98.4	4	16
2	150	50	60.3	18	120.7	4	16
2 1/2	180	65	73	20	139.7	4	16
3	190	80	88.9	22	152.4	4	16
4	230	100	114.3	24	190.5	8	16
5	255	125	141.3	24	216	8	20
6	280	150	168.3	26	241.3	8	20
8	345	200	219.1	29	298.5	8	20
10	405	250	273	32	362	12	24
12	485	300	323.9	35	432	12	24
14	535	350	355.6	38	476.3	12	27
16	595	400	406.4	41	540.5	16	27
18	635	450	457	44	578.2	16	30
20	700	500	508	48	635	20	30
24	815	600	609.6	51	749.5	20	33

Note:

Outside diameter (OD): The outside diameter of the flange.
Inside Diameter (ID): The inside diameter of the flange, relative to the pipe size.
Neck Diameter: Diameter of the flange neck.
Flange Thickness: The thickness of the flange.
Bolt Circle Diameter: The circle diameter of the bolts.
Number of Bolts: Number of bolts required to install the flange.
Bolt Diameter: Diameter of the bolt.

Summary table of common materials of Weld Neck Flanges (Code 111) according to BS 4504 standard

Material Type	Material Code (BS 4504)	Main ingredient	Characteristic	Application
Carbon steel	C22.8	Carbon, Manganese	High durability, low cost	Water, oil, gas and steam pipeline systems
Stainless Steel	1.4301 (304)	Chromium, Nickel	Good corrosion resistance, easy to process	Food, pharmaceutical, chemical industry
Stainless Steel	1.4401 (316)	Chromium, Nickel, Molybdenum	Higher corrosion resistance, acid resistance	Chemical, oil and gas, water treatment systems
Alloy Steel	16Mo3	Molybdenum, Chromium	Heat resistant, high durability	Thermal power plant, boiler, pressure system
Alloy Steel	13CrMo4-5	Chromium, Molybdenum	Heat resistant, good corrosion resistance	Chemical plant, oil and gas plant
Brass	CuZn37	Copper, Zinc	Corrosion resistant, good electrical conductivity	Seawater systems, electrical applications
Aluminum Alloy	AlMgSi1	Aluminum, Magnesium, Silicon	Lightweight, corrosion resistant	Aerospace, automotive, marine
Copper Alloy	CuNi10Fe1Mn	Copper, Nickel, Iron, Manganese	Corrosion resistant, especially in sea water	Seawater systems, marine industry