Spectacle blind flange

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Category: Pipe flanges Tag: Specialty flange

Description

A spectacle flange is a specialty flange made of two metal discs attached in the middle by a small section of steel. Spectable flanges get their name because they look like a pair of reading glasses, or spectacles. Spectacle flanges, also known as spectacle blind flanges, are most commonly used on piping systems that need to be separated regularly or where the flow through the systems is regularly stopped. One end of the spectacle flange is solid, while the other end has a hole in the center. The spectacle flange can be rotated to place either the solid or hollow end within the pipe system, thereby opening or closing the flow.

Advantages of Spectacle Flanges

Spectacle flanges require no welding for installation
Spectacle flanges from Sunny Steel Flange have a wide range of pressure tolerances
Sunny Steel will manufacture spectacle flanges to your specifications

For pipe Flanges-regularly seperated for isolation, maintenance or reasons, a spectacle extrudes Solution. Typically, spec blinds was mounted in the open position so-your flow pipe operates and is normally. Blinds is mounted onto one of the $number so is need to isolate a, it ‘ s easy!

Dimensions of spectacle blinds according to ASME B16.48

Flange spades and ring spacers, as separate products, are used when the rotation of a spectacle blind would be difficult due to space constraints. ASME B16.48 covers the dimensions and specifications of these isolation devices.

Spectacle blind
Flanges
Gaskets
Stud bolts

Spectacle blind types

The difference between spades/ring spacers and spectacle blinds is shown in the image:

Flat face spectacle blind (FF)

similar to a flat face flange, the surface of the disc is flat (suited for flat face gaskets, for low-pressure applications).

Raised face spectacle blind (RF)

likewise raised face flanges, there is an additional thickness on the surface of the disc. This type fits semi-metallic gaskets, as the spiral wound type.

Ring joint face spectacle blind (RTJ)

a groove is inscribed on the surface of the disc. This type is used in conjunction with ring joint gaskets.

Flange spade vs Spectacle blinds:

A spectacle blind combines a flange spade and a ring spacer in a single device (this is the reason why flange spades are called “single-blinds” or “blanks”). The difference is that spectacle blinds may need some space to be rotated, and this space is not always available due to the routing of the piping system. This is when two separate devices are used, as they do not require rotation to be installed.

Spades, ring spacers, and spectacle blinds are available in multiple sizes (from 1/2 inch to 24 inches, and pressure rating from 150 to 2500#) and material grades (the same available for standard flanges) depending on the fluid conveyed by the pipeline.

Ring spacer

Ring spacers are bored to the matching pipe id and are the same thickness as the “single blind” that it replaces. When removing a “single blind”, either the flange and associated piping must be pulled together to seal the line, or a “ring spacer” must be installed to fill the gap. Thick single blinds or rigid piping systems normally require ring spacers.

Single/ line blind or blank

A positive shut-off device normally installed adjacent to, or in conjunction with, a valve. Their purpose is to prevent accidental flow through a pipeline to a vessel. With the exception of cast iron, plastic, or fiberglass services, they are not drilled with bolt holes, but fit inside the bolt circle of mating flanges. Pipeline blinds or blanks are not the same as bolting blind flanges. Single blinds use standard gaskets.

A combination of a “single blind’ and a “ring spacer” can be fabricated for field convenience as a single unit. Weight consideration and the associated difficulty of handling heavy pieces in the field are a primary consideration in specifying a “spectacle blind” or a combination of blinds. Spectacle blinds are meant to be rotated to change blind/spacer orientation.

Spectacle blind

A spec blind is a combination of a ring spacer and single blind. They are usually permanently installed in a piping system and rotated as needed.

Test blank

A test blank is specially designed blank used for hydrostatic or other incompressible fluid testing purposes only. Their advantage is cost and weight savings since higher allowable stress values (or lower safety factors) are used in their design.

Vapor blind

Similar to a “single blind”, but thinner, normally 1/8″ (3mm) to 5/16″ (8mm) thick. These are positive sealing devices intended to prevent accidental flow or leakage of vapors into a pipeline or vessel, usually while the system is in service.

One end of the blind will have an opening to allow flow through the pipe during operation and the other end is solid to block flow during maintenance.

Spec Blind - line open — Spec Blind – line open

Spec Blind - line closed — Spec Blind – line closed

Spectacle blind datasheets

Spectacle Blind – ANSI Class 300 (in)
Spectacle Blind – ANSI Class 600 (in)
Spectacle Blind – ANSI Class 900 (in)
Spectacle Blind – ANSI Class 1500 (in)
Spectacle Blind – ANSI Class 2500 (in)

Standards

ASME B16.5 – Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
ASME B16.20 – Metallic Gaskets for Pipe Flanges: Ring-Joint, Spiral-Wound, and Jacketed
ASME B16.47 – Large Diameter Steel Flanges: NPS 26 Through NPS 60 Metric/Inch Standard
ASME B16.48 – Line Blanks

Types

General flange types

Flanges mostly come in six different types. However, these designs can be modified to meet the specific functions and requirements of the applications. Therefore, it’s essential to understand the pressure at the flagged joint, the required strength, and the size of pipes involved. With the correct information comes six types of flanges that an individual can choose from. These include:

Types	Description
Blind Flange	These flanges do not have a bore. It is used to blind off a flange or even a valve. When used at the end of a pipe or fitting, it provides an easy to open access for further extension of the pipe. The blind flange and its bolts are stressed more than any other flange.
Lap Joint Flange	This flange is used with a lap joint stub end fitting. It is similar to a slip-on flange, but with two differences. The radius and the flat face, both allow the flange to secure against the stub end fitting. This is useful where alignment of bolt holes is difficult, such as with spools to be attached to flanged nozzles of vessels. A lap joint is used in low pressure applications and not suitable where high external of heavy loads are present.
Slip-on Flange	Slip-on flanges are designed to slip over the outside of pipe, long-tangent elbows, reducers, and swages. The flange has poor resistance to shock and vibration. It is easier to align than a weld neck flange. This flange is ideal for low pressure applications since the strength when under internal pressure is about one third that of a weld neck flange.
Socket Weld Flange	This is similar to a slip-on flange, except they have a bored and counter bore. The counter bore allows the pipe to fit into the socket/counter bore. The bore of the flange is the same diameter as the inside of the pipe. These flanges were first designed for small diameter, high pressure pipe.
Threaded Flange	It is similar to a slip-on Flange, but has internal threads. It is normally used for low pressure and not used where temperature or stress is very high.
Weld Neck Flange	This flange comes in two types, regular and long. The hub of the weld neck is designed to reduce the stress at the base of the flange. Regular weld neck flanges are used with buttweld fittings and long weld neck flanges are usually used with equipment and vessel nozzles. A long weld neck flange is rarely used with pipe. Both types of flanges are bored to match the inside diameter of the pipe or fitting to which it will be welded to. They are suitable where high pressure, extreme temperatures, shear impact and vibratory stresses apply.

Specialty flange types

Additionally, the flanges can be modified to form other types, depending on application and functions. These unique designs are made to incorporate specific needs and applications, like reducing flanges to answer to size and orifice flanges to incorporate orifice mounting.
Other examples in this category include:

Types	Description
Spectacle blind flange	A spectacle flange is a specialty flange made of two metal discs attached in the middle by a small section of steel. Spectable flanges get their name because they look like a pair of reading glasses, or spectacles.
Reducing Flange	Reducing flanges are designed for when there is a change in the pipe size.
Orifice Flange	Orifice flanges are for metering the volumetric flow rate of liquids and gasses through a pipe. This flange is normally available in weld neck, slip-on, and threaded flanges.
Weldoflange / Nipoflange	A weldoflange is an olet connection, it is simular to a nipoflange, both are used for a branch connection on a pipe.
Expander Flange	An expander flange is similar to a weld neck flange but with the hub expanding to a larger size (one or two sizes).
Custom flanges	Our experts are exceptional at machining custom flanges for life. We have experience helping engineers, estimators, purchasing agents and more with their custom flanges.
Anchor flange	An anchor flange is a device to restrain pipe movement in a piping system,it looks like a weld neck flange but has two hubs on the both sides to weld with the pipes,but there is no bolt bores on the anchor flanges.
Standard Connection Flange	This flange is normally used for nozzles on pressure vessels and rarely used with pipe.

Categorizing pipe flanges

The most common way of classifying flanges is by considering their shapes. However, it’s essential to understand that there are other ways to categorize flanges, as these come in handy when durability, functionality, and application are in question. These include:

Classification by material used includes brass, alloy steel, cast iron, carbon steel, stainless steel, aluminum, or PVC.
Classification by flange face includes flat, ring joint, raised, female and male, lap joint, tongue, and groove.
Classification by piping flange dimensions, which include pressure rating or nominal size.
Classification by flange finish, which gives smooth, stock, or serrated.

Flange Types in three groups

Remember the types of flanges described in the beginning of this article? (Welding Neck, Slip-On, Threaded, Socket Weld, Lap-Joint and Blind), well those were the standard types, now you’ll see that the types of flanges available in the type of the flange is very similar to them, so all the “pros” and “cons” described there can be applied here.

The types divided the flanges in three groups: loose, integral and optional. Below I’ll describe these types according to the Code.

Loose Type Flanges:

This type covers those designs in which the flange has no direct connection to the nozzle neck, vessel, or pipe wall, and designs where the method of attachment is not considered to give the mechanical strength equivalent of integral attachment.

Integral Type Flanges:

This type covers designs where the flange is cast or forged integrally with the nozzle neck, vessel or pipe wall, butt welded thereto, or attached by other forms of arc or gas welding of such a nature that the flange and nozzle neck, vessel or pipe wall is considered to be the equivalent of an integral structure. In welded construction, the nozzle neck, vessel, or pipe wall is considered to act as a hub.

Optional Type Flanges:

This type covers designs where the attachment of the flange to the nozzle neck, vessel or pipe wall is such that the assembly is considered to act as a unit, which shall be calculated as an integral flange, except that for simplicity the designer may calculate the construction as a loose type flange provided none of the following values is exceeded: g0 = 5/8″ (16 mm), B/g0 = 300, P = 300 psi (2 MPa) and operating temperature = 700°F (370°C).

Standards

Pipe Flange Standards mainly include three systems in the world, ANSI/ASME flange system(American), DIN flange system(European system), JIS flange system, other system made according to this three systems, like GB flange standard, which mainly made according to ANSI/ASME and DIN flange standard, Duwa Piping supplies those flanges with top quality and soonest delivery time.

ASME standards

ASME B16.1 – Gray Iron Pipe Flanges and Flanged Fittings: Classes 25, 125, and 250
ASME B16.5 – Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
ASME B16.20 – Ring Joint Gaskets and Grooves for Steel Pipe Flanges
ASME B16.21 – Nonmetallic Flat Gaskets for Pipe Flanges
ASME B16.24 – Cast Copper Alloy Pipe Flanges and Flanged Fittings: Classes 150, 300, 600, 900, 1500, and 2500
ASME B16.34 – Large Diameter Steel Flanges (NPS 26 through NPS 60)
ASME B16.36 – Orifice Flanges
ASME B16.42 – Ductile Iron Pipe Flanges and Flanged Fittings: Classes 150 and 300
ASME B16.47 – Large Diameter Steel Flanges (NPS 26 Through NPS 60)

ASTM standards

ASTM A105 – Specification for Carbon Steel Forgings for Piping Applications
ASTM A182 – Specification for Forged or Rolled Alloy Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High Temperature Service
ASTM A193 – Specification for Alloy Steel and Stainless Steel Bolting Materials for High Temperature Service
ASTM A194 – Specification for Carbon and Alloy Steel Nuts for Bolts for High Pressure and High Temperature Service
ASTM A694 – Specification for Carbon and Alloy Steel Forgings for Pipe Flanges, Fittings, Valves, and Parts for High-Pressure Transmission Service
ASTM A707 – Specification for Flanges, Forged, Carbon and Allow Steel for Low Temperature Service

AWWA standards

AWWA C115 – Standard for Flanged Ductile Iron Pipe with Ductile-Iron or Gray-Iron Threaded Flanges

ISO standards

ISO 5251 – Stainless steel butt-welding fittings

MSS standards

MSS SP-6 – Standard Finishes for Contact Faces Pipe Flanges and Connecting End Flanges of Valves and Fittings
MSS SP-9 – Spot Facing for Bronze, Iron and Steel Flanges
MSS SP-25 – Standard Marking Systems for Valves, Fittings, Flanges, and Unions
MSS SP-44 – Steel Pipeline Flanges
MSS SP-53 – Quality Standards for Steel Castings and Forgings for Valves, Flanges and Fittings and Other Piping Components – Magnetic Particle
MSS SP-54 – Quality Standards for Steel Castings and for Valves, Flanges and Fittings and Other Piping Components – Radiographic
MSS SP-55 – Quality Standards for Steel Castings and for Valves, Flanges and Fittings and Other Piping Components – Visual
MSS SP-75 – High Test Wrought Butt Welding Fittings
MSS SP-106 – Cast Copper Alloy Flanges and Flanged Fittings Class 125,150, and 300
ASME B16.5 and ASME B16.47 cover pipe flanges up to NPS 60 (B16.5 from 1/2″ to 24″ and B16.47 from 26″ to 60″). ANSI B16.47 covers two series of flanges, Series A is equal to MSS SP-44-44, and Series B is equal to API 605 (API 605 has been canclled).

Facing

There are three primary types of flange facings. Not all facings are available with each end connection. This is based on the design of the flange and design of the piping system.

The typical flange facings are: Flange facing types

Raised Face Flanges (RF)

Raised face flange has a small portion around the bore is raised from the face. The gasket seat on this raised face. The height of the raised face depends on the flange pressure-temperature rating that is known as a class of the flange. For 150# & 300# height of the raised face is 1/6” and above 300# it is 1/4”. The inside bore circle type of gasket is used with a raised face flange.

Flat Face Flanges (FF)

As the name suggests, the flat face flange has a flat face. Flat face flanges are used when the counter-flanges are flat faces. This condition occurs mainly in connection to Cast Iron equipment, valves, and specialties. A full-face gasket is used when a flat face flange is used.

Ring Type Joint Flanges (RTJ)

Ring joint type face flange has a specially designed grove in which metal gasket seat. This type of flange is used in high pressure and temperature services.

Flange facing types according to DIN EN 1092-1

Flanges and their joints – Circular flanges for pipes, valves, fittings and accessories, PN designated – Part 1: Steel flanges

This European standard specifies requirements for circular steel flanges in PN designations PN 2,5 to PN 400 and nominal sizes from DN 10 to DN 4000. This standard specifies the flange types and their facings, dimensions, tolerances, threading, bolt sizes, flange face surface finish, marking, materials, pressure/ temperature ratings and flange masses.

Flange faces have to be smooth enough to ensure a tight, leak-free seal for bolted flanges.

Type A: flat face	Type D: groove face	Type G: O Ring recess
Type B: raised face	Type E: spigot	Type H: O Ring groove
Type C: tongue face	Type F: recess

Flange facing types according to DIN EN 1092-1

Flange facing dimensions

DN	PN												f1	f2	f3	f4	w	x	y	z	α	R
	2.5	6	10	16	25	40	63	100	160	250	320	400
	d1
10	35	35	40	40	40	40	40	40	40	40	40	40	2	4.5	4	2	24	34	35	23	-	2.5
15	40	40	45	45	45	45	45	45	45	45	45	45					29	39	40	28	-
20	50	50	58	58	58	58	58	58	58	58	58	58					36	50	51	35	41º
25	60	60	68	68	68	68	68	68	68	68	68	68					43	57	58	42
32	70	70	78	78	78	78	78	78	78	78	78	78					51	65	66	50
40	80	80	88	88	88	88	88	88	88	88	88	88	3				61	75	76	60
50	90	90	102	102	102	102	102	102	102	102	102	102					73	87	88	72
65	110	110	122	122	122	122	122	122	122	122	122	122					95	109	110	94
80	128	128	138	138	138	138	138	138	138	138	138	138					106	120	121	105
100	148	148	158	158	162	162	162	162	162	162	162	162		5	4.5	2.5	129	149	150	128	32º	3
125	178	178	188	188	188	188	188	188	188	188	188	188					155	175	176	154
150	202	202	212	212	218	218	218	218	218	218	218	218					183	203	204	182
200	258	258	268	268	278	285	285	285	285	285	285	285					239	259	260	238
250	312	312	320	320	335	345	345	345	345	345	345	-					292	312	313	291
300	365	365	370	378	395	410	410	410	410	-	-	-	4				343	363	364	342
350	415	415	430	438	450	465	465	465	-	-	-	-		5.5	5	3	395	421	422	394	27º	3.5
400	465	465	482	490	505	535	535	535	-	-	-	-					447	473	474	446
450	520	520	532	550	555	560	560	560	-	-	-	-					497	523	524	496
500	570	570	585	610	615	615	615	615	-	-	-	-					349	375	376	548
600	670	670	685	725	720	735	735	-	-	-	-	-	5				649	675	676	648
700	775	775	800	795	820	840	840	-	-	-	-	-					751	777	778	750
800	880	880	905	900	930	960	960	-	-	-	-	-					856	882	883	855
900	980	980	1005	1000	1030	1070	1070	-	-	-	-	-					961	987	988	960
1000	1080	1080	1110	115	1140	1180	1180	-	-	-	-	-		6.5	6	4	1062	1092	1094	1060	28º	4
1200	1280	1295	1330	1330	1350	1380	1380	-	-	-	-	-					1262	1292	1294	1260
1400	1480	1510	1535	1530	1560	1600	-	-	-	-	-	-					1462	1492	1494	1460
1600	1690	1710	1760	1750	1780	1815	-	-	-	-	-	-					1662	1692	1694	1660
1800	1890	1920	1960	1950	1985	-	-	-	-	-	-	-					1862	1892	1894	1860
2000	2090	2125	2170	2150	-	-	-	-	-	-	-	-					2062	2092	2094	2060
2200	2295	2335	2370	-	-	-	-	-	-	-	-	-		-	-	-	-	-	-	-	-	-
2400	2495	2545	2570	-	-	-	-	-	-	-	-	-		-	-	-	-	-	-	-	-	-
2600	2695	2750	2780	-	-	-	-	-	-	-	-	-		-	-	-	-	-	-	-	-	-
2800	2910	2960	2000	-	-	-	-	-	-	-	-	-		-	-		-	-	-	-	-	-
3000	3110	3160	3210	-	-	-	-	-	-	-	-	-		-	-	-	-	-	-	-	-	-
3200	3310	3370	-	-	-	-	-	-	-	-	-	-		-	-	-	-	-	-	-	-	-
3400	3510	3580	-	-	-	-	-	-	-	-	-	-		-	-	-	-	-	-	-	-	-
3600	3720	3790	-	-	-	-	-	-	-	-	-	-		-	-	-	-	-	-	-	-	-
3800	3920	-	-	-	-	-	-	-	-	-	-	-		-	-	-	-	-	-	-	-	-
4000	4120	-	-	-	-	-	-	-	-	-	-	-		-	-	-	-	-	-	-	-	-

units [mm]
Flange facing types C, D, E, F, G and H are not used for PN 2,5 and PN 6.
Flange facing types G and H are only used for PN 10 to PN 40.

The type of forged flange and sealing face for flange

Flanges provide the necessary connections to link pipelines. Faces are the mating surface of a flange.

Different types of flange faces are used as the contact surfaces to seat the sealing gasket material.

The type of flange	The type of sealing face	Pressure Class(PN,MPA)
Plate flange(PL)	Raise Face(RF)	0.25-2.5
Plate flange(PL)	Flat Face( FF)	0.25-1.6
Slip on flange(SO)	Raise Face(RF)	0.6-4.0
	Flat Face( FF)	0.6-1.6
	male and female face (MFM)	1.0-4.0
	Tongue and groove face (TG)	1.0-4.0
Welding Neck Flange(WN)	Raise Face(RF)	1.0-25.0
	male and female face (MFM)	1.0-16.0
	Tongue and groove face (TG)	1.0-16.0
	Ring Joint Face(RTJ)	6.3-25.0
	Flat Face( FF)	1.0-1.6
Integral type flange(IF)	Raise Face(RF)	0.6-25.0
	male and female face (MFM)	1.0-16.0
	Tongue and groove face (TG)	1.0-16.0
	Ring Joint Face(RTJ)	6.3-25.0
	Flat Face( FF)	0.6-1.6
Socket Weld Flange(SW)	Raise Face(RF)	1.0-10.0
	male and female face (MFM)	1.0-10.0
	Tongue and groove face (TG)	1.0-10.0
Thread Flange(Th)	Raise Face(RF)	0.6-4.0
Thread Flange(Th)	Flat Face( FF)	0.6-1.6
Lap joint Flange(LP)	Raise Face(RF)	0.6-1.6
	male and female face (MFM)	1.0-1.6
	Tongue and groove face (TG)	1.0-1.6
Blind flange(BL)	Raise Face(RF)	0.25-25.0
	male and female face (MFM)	1.0-16.0
	Tongue and groove face (TG)	1.0-16.0
	Ring Joint Face(RTJ)	6.3-25.0
	Flat Face( FF)	0.25-1.6

Other flange facings covered by these standards include the large and small tongue-and-groove facings, and the ring joint facing specifically for ring joint type metal gaskets.

Materials

Flanges are welded to pipe and equipment nozzle. Accordingly, it is manufactured from the following materials;

Carbon steel
Low alloy steel
Stainless steel
Combination of Exotic materials (Stub) and other backing materials

The list of materials used in manufacturing is covered in ASME B16.5 & B16.47.

ASME B16.5 -Pipe Flanges and Flanged Fittings NPS ½” to 24”
ASME B16.47 -Large Diameter Steel Flanges NPS 26” to 60”

Commonly used Forged material grads are

Carbon Steel: – ASTM A105, ASTM A350 LF1/2, ASTM A181
Alloy Steel: – ASTM A182F1 /F2 /F5 /F7 /F9 /F11 /F12 /F22
Stainless Steel: – ASTM A182F6 /F304 /F304L /F316 /F316L/ F321/F347/F348

Frequently used astm grades

Material	Fittings	Flanges	Valves	Bolts & Nuts
Carbon Steel	A234 Gr WPA	A105	A216 Gr WCB	A193 Gr B7 A194 Gr 2H
	A234 Gr WPB	A105	A216 Gr WCB
	A234 Gr WPC	A105	A216 Gr WCB
Carbon Steel Alloy High-Temp	A234 Gr WP1	A182 Gr F1	A217 Gr WC1	A193 Gr B7 A194 Gr 2H
	A234 Gr WP11	A182 Gr F11	A217 Gr WC6
	A234 Gr WP12	A182 Gr F12	A217 Gr WC6
	A234 Gr WP22	A182 Gr F22	A217 Gr WC9
	A234 Gr WP5	A182 Gr F5	A217 Gr C5
	A234 Gr WP9	A182 Gr F9	A217 Gr C12
Carbon Steel Alloy Low-Temp	A420 Gr WPL6	A350 Gr LF2	A352 Gr LCB	A320 Gr L7 A194 Gr 7
Carbon Steel Alloy Low-Temp	A420 Gr WPL3	A350 Gr LF3	A352 Gr LC3	A320 Gr L7 A194 Gr 7
Austenitic Stainless Steel	A403 Gr WP304	A182 Gr F304	A182 Gr F304	A193 Gr B8 A194 Gr 8
	A403 Gr WP316	A182 Gr F316	A182 Gr F316
	A403 Gr WP321	A182 Gr F321	A182 Gr F321
	A403 Gr WP347	A182 Gr F347	A182 Gr F347

ASTM standards define the specific manufacturing process of the material and determine the exact chemical composition of pipes, fittings and flanges, through percentages of the permitted quantities of carbon, magnesium, nickel, etc., and are indicated by "Grade".

The usual materials of flanges include stainless steel, carbon steel, aluminum and plastic. The choice of the material largely depends on the purpose of the flange. For example, stainless steel is more durable and is necessary for heavy use. On the other hand, plastic is more feasible for use in the home because of its reasonable price and easy installation. The materials used for flanges are under the designation of the American Society of Mechanical Engineers.

Flange materials acc. to ASTM

The most common materials for pipe flanges (forged grades) are: ASTM A105 (carbon steel high temperature to match A53/A106/API 5L pipes), A350 Grades LF1/2/3 (carbon steel low temperature to match A333 pipes), A694 Grades F42 to F80 (high yield carbon steel to match API 5L pipe grades), ASTM A182 Grades F5 to F91 (alloy steel flanges to match A335 pipes), A182 Grade F304/316 (stainless steel flanges to match A312 SS pipes), A182 Gr. F44/F51/F53/F55 (duplex and super duplex to match A790/A928 pipes) and various nickel alloy grades (Inconel, Incoloy, Hastelloy, Monel).

The material qualities for these flanges are defined in the ASTM standards.

What are ASTM Grades?
For example, a carbon steel pipe can be identified with Grade A or B, a stainless-steel pipe with Grade TP304 or Grade TP321, a carbon steel fitting with Grade WPB etc.

Chemical Composition (%) of ASTM A403

Steel No.	Type	C	Si	S	P	Mn	Cr	Ni	Mo	Other	ób	ós
WP304	0.08	1	0.03	0.045	2	18-20	8-11			515	205	28
WP304H	0.04-0.1	1	0.03	0.045	2	18-20	8-11			515	205	28
WP304L	0.035	1	0.03	0.045	2	18-20	8-13			485	170	28
WP304LN	0.03	0.75	0.03	0.045	2	18-20	8-10.5		N2:0.1-0.16	515	205	28
WP304N	0.08	0.75	0.03	0.045	2	18-20	8-11		N2:0.1-0.16	550	240	28
WP309	0.15	1	0.03	0.045	2	22-24	12-15			515	205	28
WP310	0.15	1.5	0.03	0.045	2	24-26	19-22			515	205	28
WP316	0.08	1	0.03	0.045	2	16-18	10-14	2-3		515	205	28
WP316H	0.04-0.1	1	0.03	0.045	2	16-18	10-14	2-3		515	205	28
WP316LN	0.03	0.75	0.03	0.045	2	16-18	11-14	2-3	N2:0.1-0.16	515	205	28
WP316L	0.035	1	0.03	0.045	2	16-18	10-16	2-3		485	170	28
WP316N	0.08	0.75	0.03	0.045	2	16-18	11-14	2-3	N2:0.1-0.16	550	240	28
WP317	0.08	1	0.03	0.045	2	18-20	11-15	3-4		515	205	28
WP317L	0.03	1	0.03	0.045	2	18-20	11-15	3-4		515	205	28
WP321	0.08	1	0.03	0.045	2	17-20	9-13		Ti:5C-0.7	515	205	28
WP321H	0.04-0.1	1	0.03	0.045	2	17-20	9-13		Ti:4C-0.7	515	205	28
WP347	0.08	1	0.03	0.045	2	17-20	9-13		Nb+Ta:10C-1.1	515	205	28
WP347H	0.04-0.1	1	0.03	0.045	2	17-20	9-13		Nb+Ta:8C-1	515	205	28
WP348	0.08	1	0.03	0.045	2	17-20	9-13		Ta:0.1	515	205	28
WP348H	0.04-0.1	1	0.03	0.045	2	17-20	9-13		Ta:0.1	515	205	28

Notes:

For each reduction of 0.01% below the specified C maximum, an increase of 0.06% Mn above the specified maximum will be permitted, up to a maximum of 1.35%.
The sum of Cu, Ni, Cr, and Mo shall not exceed 1.00%.
The sum of Cr and Mo shall not exceed 0.32%.
The maximum carbon equivalent (C.E.) shall be 0.50, based on heat analysis and the formula C.E.=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15.

Mechanical properties of ASTM A403

Grade	UNS	Tensile Strength, min		Yield Strength,min		Elongation min % in 4D
		ksi	MPa	ksi	MPa	Longit %	Trans%
ALL	ALL	75	515	30	205	28	20
304L	S30403	70	485	25	170	28	20
316L	S31603	70	485	25	170	28	20
304N	S30451	80	550	35	240	28	20
316N	S31651	80	550	35	240	28	20
316N	S31726	80	550	35	240	28	20
XM-19	S20910	100	690	55	380	28	20
	S31254	94-119	650-820	44	300	28	20
	S34565	115	795	60	415	28	20
	S33228	73	500	27	185	28	20

Faqs

The most frequently asked questions regarding flanges and flange fittings have to do with how flanges fit on specific steel tube and steel pipe ends.

How flanges operate?

Flanges have flat or flush surfaces that are vertical to the pipe to which they are attached. The attachment process involves mechanically joining two or more faces using bolts, adhesives, collars, or welds. Due to the attachment requirements, a flange must fit the equipment or pipe that it’s designed. That’s why it’s necessary to check all the possible specifications and dimensions to ascertain that it’s of the right size, type, and material.

What are the three parts of a flanged connection?

Pipe flanges, gaskets, and bolts are the three parts that comprise a flanged connection. Gaskets and bolts are typically made of the same flange materials or a material approved for the pipe components. Each component comes in various materials that suit specific applications and must be matched correctly for proper functioning. The gaskets come in two conventional types: full-face gaskets and ring gaskets. Full-face gaskets have the bolt holes visible and pair up with raised-face gaskets. Ring gaskets tend to be smaller rings minus the bolt holes and pair up with flat-faced flanges. Securing the flange components requires matching the surfaces evenly and plumb, adjusting as needed for a uniform fit. Once all surfaces match, bring the flanges together and secure at least two of the bolts. Refine the alignment, so the remaining bolt holes match and their corresponding bolts are tightly secured.

How do I properly size a flange for pipe use?

Properly sizing a flange for pipe use depends not only on the type of flange but its compatible piping. The pipe must slip into the flange’s inside diameter easily and securely, and the outside diameter should cover wall holes. Once you determine the specific flange type and material you need for the job, you’ll need to take several measurements. The four measurements you’ll need are the inside diameter, outside diameter, bolt hole count, and bolt hole center. You’ll need to align each of these measurements from opposing bolt holes to get the most accurate readings. Take all measurements from edge to edge and try to get as precise as possible to match the correct product. Round up bolt diameter to the next half or whole step since bolts measure half or whole inches. Once you have all four measurements, check them against the manufacturer’s table to find the correct flange. Most manufacturers list these specifications on their websites for easy reference.

Flange Inspection

Before dispatching from manufacture each flange is inspected to ensure quality. During an inspection you have to check the following;

Outer & Inner Diameter of body
Bolt Circle & Bolt hole Diameter
Hub Diameter & thickness of weld end
Length of the Hub
Straightness and alignment of the bolt hole

ASME B16.5 and B16.47 standards cover permissible tolerances for inspection.

Applications

When a piping joint requires to be dismantled, flanges are being used. These are primarily used on equipment, valves, and specialty items. Breakout flanges are provided at predetermined intervals in certain pipelines where maintenance is a regular occurrence. The flanges, gaskets, and bolting make up a flanged joint, which is made up of three separate but interconnected components. To achieve a leak-proof joint, special controls are required in the selection and application of all of these elements.

Here are the details of Flanges about their advantages and their applications.

Advantages of Flanges

Pipes, valves, pumps, and other parts are connected with flanges to form a piping system. Generally, flanges are welded or screwed together. The use of flanges makes pipe system maintenance and repair a breeze. Instead of taking the entire pipe for inspection, a small section of the pipe can be carefully investigated to use a flange to locate the fault.

The following are the five most important benefits of The following are the five most important benefits of flanges:

Easy assembly in tight spaces where wrenches may not have clearance if traditional flange fittings are used. With moderate torque, they’re easier to put together.
In hard-to-reach areas where flexibility is required, adapters in the hose line, pipe, or tube can be removed.
Pipe connections, tubes, or large hose links with high pressure, vibration, or shock pressures that could damage traditional large hydraulic fittings more easily.
In rigid lines such as metal tubes or continuous pipes, making connections allows for easy maintenance.
In demanding hydraulic applications, reduce the chance of components becoming loose.

A flange is a method of connecting pipes, valves, pumps, and other equipment to form a piping system. It also provides easy access for cleaning, inspection, or modification. Flanges are usually welded or screwed.

In many applications, engineers need to find a way to close off a chamber or cylinder in a very secure fashion, usually because the substance inside must differ from the substance outside in composition or pressure.

They do this by fastening two pieces of metal or other material together with a circle of bolts on a lip. This “lip” is a flange.

Plumbing

You can connect two sections of metal piping by soldering or welding them together, but pipes connected in this way are very susceptible to bursting at high pressures. A way of connecting two sections of pipe more securely is by having flanged ends that you can connect with bolts. This way, even if gases or liquids build up to high pressures inside the pipe, it will often hold with no problem.

Mechanics

In order to connect two sections of a large, enclosed area, it is often best to used flanges and bolts. An example of this is the connection between the engine and the transmission in an automobile. In this case, both the engine and the transmission contain a number of moving parts that can easily get damaged if they get dust or other small objects inside of them. By connecting the outer casings of the engine and transmission in this way, engineers protect the inner workings of both.

Electronics

Flanges have a specific purpose in cameras and other electronic devices. Though flanges in such items do not usually have to sustain high pressures, they do have to hold tight so they can keep out harmful particles. These flanges are usually found connecting two different materials, such as the glass of a lens and the rest of the body of the camera.

Flanged connection

There are many ways to connect flanges, including threading, welding or bolting. The threaded flange is best for low pressure or smaller pipelines because it can maintain its seal. When your pipeline is larger or high pressure, then the welded flange is preferable. A boiler room is one place where welded blind flanges might be used, due to the high pressure involved.

Flanged joints: flanges, bolts and nuts and gaskets

A flange is a external rib at the end of pipes, valves and other flow devices to assemble them.

Dimensions of the flanges are up to specific Standards : DIN, ANSI, AS, BS, JIS

A flanged connection requires two flanges (the “main” and the “companion”), a set of bolts and nuts (whose number depends on the flange diameter and class) and two sealing gaskets. Flanged connections have to be executed and supervised by trained personnel, as the quality of the joint has a critical impact on the performance of the piping system / pipeline (the standard TSE – TS EN 1591 Part 1-4, “Flanges and their joints”, defines a number of requirements for the execution of proper flanged connections). Whereas all elements of the joint are critical, experience shows most leaks are originated by the improper installation of the sealing elements, i.e. the gaskets.

The typical pipe to flange connections are welded or threaded. Welded flanges are used for pipelines and piping systems with high pressures and temperatures, and with diameters above 2 inches.

Threaded connections are instead used for installations of smaller diameter and not subject to severe mechanical forces such as expansion, vibration, contraction, oscillation (forces that would crack the threaded joint). In all these critical cases, butt weld connections are recommended.