AS4087 PN21 Stainless Steel Flanges Slip on and Blind Flange

AS4087 PN21 Flanges Manufacturer

We are a professional manufacturer, exporter, and supplier of AS 4087 PN21 flanges, produced according to the Australian Standard AS 4087 for metallic flanges used in water and wastewater pipeline systems.
Our PN21 flanges are designed for medium-pressure applications and are widely used in water supply networks, desalination plants, power stations, and industrial pipelines.

AS4087 PN21 is the same drilling and rating as AS2129 Table F

AS 4087 specified the metallic flanges for waterworks purposes and installers of flanged components guidance on the most appropriate jointing requirements to achieve a satisfactory long-term watertight joint.

⬇️Download AS-4087 Standard Now (PDF)

AS4087 is the latest standard for BS table D to H, the same drilling is used but the new PN pressure rating system has been adopted. As the new pressure ratings are slightly higher the flange thicknesses have slightly increased. Also the raised face dimensions (although rarely specified, flat face is mostly used) are slightly larger. Table C, J to R, no longer exist, PN16 is the same drilling as Table D, PN21 is the same as Table E, PN35 is the same as Table H.

AS 4087 Flange Type

AS 4087 PN21 Flanges for PE Stub are typically lap joint or backing flanges designed to match with PE stub ends (butt-fused or electro-fused). This combination lets you connect polyethylene pipe to metal components (such as valves, equipment, or pipeline segments) with ease, while retaining maximum resistance to corrosion and pressure.

AS 4087 Flange Size Range

✅ Nominal Size (DN): DN 20 to DN 1200
✅ Flange Thickness: varies by pressure class and size
✅ Flange Facing: flat face (typically) for proper gasket seating
✅ Flange Drilling: to AS 4087 P21 standard (with standard number of holes, P.C.D, and hole size)

What Are AS4087 PN21 Flanges?

AS4087 PN21 flanges are flat-faced flanges used in pressure-rated pipe systems. PN21 corresponds to a maximum pressure rating of 2100 kPa and is equivalent to AS2129 Table F drilling. These flanges are widely used in:

Water infrastructure and treatment plants
Fire protection piping
Irrigation systems
General industrial pipeline connections

We manufacture and supply a full range of AS4087 PN21 flanges, including:

AS 4087 PN21 Weld Neck Flange
AS 4087 PN21 Slip On Flange
AS 4087 PN21 Blind Flange
AS 4087 PN21 Threaded Flange
AS 4087 PN21 Plate Flange
AS 4087 PN21 Lap Joint Flange
Sizes from DN50 to DN600 (2” to 24”)

Grade Specifications for 316L Stainless Steel

Grade	UNS No	Old British		Euronorm		Swedish SS	Japanese JIS
Grade	UNS No	BS	En	No	Name	Swedish SS	Japanese JIS
316L	S31603	316S11	–	1.4404	X2CrNiMo17-12-2	2348	SUS 316L

AS 4087 PN21 Blind Flanges & AS 4087 PN21 Slip on Flanges Dimensions

PN21			FLANGE THICKNESS	DRILLING DATA				PN21
NOMINAL PIPE SIZE		FLANGE OUTSIDE DIAMETER	THICKNESS OF FLANGE	PITCH CIRCLE DIAMETER	BOLT HOLE DIAMETER	NUMBER OF BOLT HOLES	NOMINAL PIPE SIZE
MM	INCH	OD	T	PCD	H	#	MM	INCH

50	2	165	15	127	18	4	50	2
65	2 1/2	185	15	146	18	8	65	2 1/2
80	3	205	15	165	18	8	80	3
100	4	230	19	191	18	8	100	4
150	6	305	24	260	22	12	150	6
200	8	370	24	324	22	12	200	8
225	9	405	30	356	26	12	225	9
250	10	430	30	381	26	12	250	10
300	12	490	30	438	26	16	300	12
350	14	550	30	495	30	16	350	14
375	15	580	38	521	30	16	375	15
400	16	610	38	552	30	20	400	16
450	18	675	38	610	33	20	450	18
500	20	735	48	673	33	24	500	20
600	24	850	58	781	36	24	600	24
700	28	935	58	857	36	24	700	28
750	30	1015	58	940	36	28	750	30
800	32	1060	68	984	36	28	800	32
900	36	1185	68	1105	39	32	900	36
1000	40	1275	78	1194	39	36	1000	40
1200	48	1530	88	1441	42	40	1200	48

NOTES:

(1) Stocked flanges are generally supplied as flat face

(2) Raised face or “O” ring groove also available.

(3) Flanges may also be supplied in weld neck and bossed configuration. (hub dimensions as per AS2129)

Application of AS 4087 Backing ring flanges

✅ Water Supply and Distribution
✅ Irrigation Pipelines
✅ Wastewater and Drainage
✅ Industrial Fluid Handling
✅ Desalination and Water Treatment
✅ Connection Between PE and Steel Pipelines

Order Example

Product: AS 4087 PN21 Weld Neck Flange
Material: ASTM A182 F316L
Size: DN200 (8”)
Facing: Raised Face (RF)
Quantity: 30 pcs
Standard: AS 4087 PN21 / EN 10204 3.1