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Lap Joint Flange

Lap joint flange is used with a lap joint stub end fitting. Lap joint flange 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.

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Description

lap joint flange typeLap joint flange is used with a lap joint stub end fitting. Lap joint flange 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.

These flanges are always used with either a stub end or taft which is butt welded to the pipe with the flange loose behind it. This means the stub end or taft always makes the face. The lap joint is favoured in low pressure applications because it is easily assembled and aligned. To reduce cost these flanges can be supplied without a hub and/or in treated, coated carbon steel.

Lap joint flanges are usually used in low pressure applications and are not suitable when there are high loads on the flange pair. Some types of piping require the use of lap joint flanges. For example, metallic pipe that has been plastic lining may have lap joint flanges.

Using lap joint flanges might be an option for saving costs when the piping is made of exotic materials. By using a lap joint flange, the wetted materials would consist of the exotic materials and the flange would be carbon steel. Since the flange doesn’t ever come in contact with the process fluid, it would not be affected by the fluids.

Dimensions on the lap joint flange are similar to weld neck, slip on or socket weld flanges. The backing flange has the same number of bolt holes, size and thickness of a weld neck or slip on flange.

Stub end

Stubend geometry
There are three different types of stub ends, Type A, B and C. Type A stub ends are machined to fit in a standard lap joint backing flange. The mating surfaces are shaped with the same profile to allow for uniform loading of the flare face. Type B stub ends are ends that are designed to be used with a standard slip on flange. Both Type A & B stub ends are either cast or forged.

Type C ends are designed to be used with either a lap joint flange or a slip on flange. Type C ends are fabricated from pipe. The most common type of fabrication is through the use of a machine flare. This is done by using a machine to flare the end of the pipe and then cutting it to length.

The stub end is available in two separate lengths, a short pattern and a long pattern. Long pattern ends are also known as ASA Stub Ends. Short pattern ends are used with larger flanges for ANSI 300 & 600. They generally are used for most sizes ANSI 900 & above.

Some applications of Lap joint flanges

Furthermore, a standard lap joint flange will typically have a longer hub length in comparison to a slip on flange, but this is often considered unnecessary for many applications.

Ceramic lined lateral pipe wye

Ceramic Lined Lateral pipe Wye from a single spool piece to complete piping systems.

The lap joint flange is practically identical to a slip-on flange except it has a radius at the intersection of the bore and flange face.

Wear and corrosion resistant Y shape pipe

Ceramic lined Bend with flange

Alumina ceramic lined wear resistant bends

With the support of our experienced professionals, our enterprise has established in this domain as a reputed manufacturer, exporter and supplier of Ceramic Lined Bends.

The lap joint flange is practically identical to a slip-on flange except it has a radius at the intersection of the bore and flange face. This radius is necessary to have the flange accommodate a lap joint stub end. Normally, a lap joint flange and a lap joint stub end are mated together is an assembly system.

Lap joint flange datasheets

The datasheets we have on this site are shown below.  For simplicity sake, only datasheets that adhere to B16.5 are shown.  ASME B16.5 covers flange dimensions from ½” to 24”.  For sizes larger than this (ASME B16.47 Series A & B), please visit our flange datasheets page. 
ClassFlat Face
ANSI 150Lap Joint, ANSI Class 150 (in)
ANSI 300Lap Joint, ANSI Class 300 (in)
ANSI 400Lap Joint, ANSI Class 400 (in)
ANSI 600Lap Joint, ANSI Class 600 (in)
ANSI 900Lap Joint, ANSI Class 900 (in)
ANSI 1500Lap Joint, ANSI Class 1500 (in)
ANSI 2500Lap Joint, ANSI Class 2500 (in)

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:
TypesDescription
Blind FlangeThese 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 FlangeThis 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 FlangeSlip-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 FlangeThis 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 FlangeIt 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 FlangeThis 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:
TypesDescription
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 FlangeReducing flanges are designed for when there is a change in the pipe size.
Orifice FlangeOrifice 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 / NipoflangeA 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 flangeAn 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 FlangeThis 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).

Classes

Only the most used flange classes are listed on this page. For more information on flanges and their respective standards, please follow the link below.

150 300 400 600 900 1500 2500

The concept of flange ratings likes clearly. A Class 300 flange can handle more pressure than a Class 150 flange, because a Class 300 flange are constructed with more metal and can withstand more pressure. However, there are a number of factors that can impact the pressure capability of a flange.

The Pressure Class or Rating for flanges will be given in pounds. Different names are used to indicate a Pressure Class.
For example: 150 Lb or 150 Lbs or 150# or Class 150, all are means the same.

The concept of flange ratings likes clearly. A Class 300 flange can handle more pressure than a Class 150 flange, because a Class 300 flange are constructed with more metal and can withstand more pressure. However, there are a number of factors that can impact the pressure capability of a flange.
The Pressure Class or Rating for flanges will be given in pounds. Different names are used to indicate a Pressure Class.
For example: 150 Lb or 150 Lbs or 150# or Class 150, all are means the same.

ASME B16.5 covers flanges with a nominal size from 1/2″ through 24″. It also includes classes from ANSI 150 through ANSI 2500. The flanges included in B16.5 are blind, lap joint, socket, slip-on, threaded and weld neck flanges.

ASME B16.47 covers flange with a nominal size of 24″ and larger. The flange classes it covers are from ANSI 75 through ANSI 900. The flanges included are blind and weld neck flanges. Additionally, B16.47 has two series of flanges, Series A (similar to ASME MSS SP44) & Series B (similar to API 605). Series A flanges are larger, heavier and have fewer bolt holes. The reason for series A and series B is that both specifications mentioned before were brought together to be covered under ASME B16.47.

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 faceType D: groove faceType G: O Ring recess
Type B: raised faceType E: spigotType H: O Ring groove
Type C: tongue faceType F: recess

Flange facing types according to DIN EN 1092-1

Flange facing dimensions

DNPNf1f2f3f4wxyzαR
2.561016254063100160250320400
d1
1035354040404040404040404024.54224343523-2.5
1540404545454545454545454529394028-
205050585858585858585858583650513541º
2560606868686868686868686843575842
3270707878787878787878787851656650
40808088888888888888888888361757660
50909010210210210210210210210210210273878872
651101101221221221221221221221221221229510911094
80128128138138138138138138138138138138106120121105
10014814815815816216216216216216216216254.52.512914915012832º3
125178178188188188188188188188188188188155175176154
150202202212212218218218218218218218218183203204182
200258258268268278285285285285285285285239259260238
250312312320320335345345345345345345-292312313291
300365365370378395410410410410---4343363364342
350415415430438450465465465----5.55339542142239427º3.5
400465465482490505535535535----447473474446
450520520532550555560560560----497523524496
500570570585610615615615615----349375376548
600670670685725720735735-----5649675676648
700775775800795820840840-----751777778750
800880880905900930960960-----856882883855
90098098010051000103010701070-----961987988960
1000108010801110115114011801180-----6.564106210921094106028º4
12001280129513301330135013801380-----1262129212941260
1400148015101535153015601600------1462149214941460
1600169017101760175017801815------1662169216941660
180018901920196019501985-------1862189218941860
20002090212521702150--------2062209220942060
2200229523352370------------------
2400249525452570------------------
2600269527502780------------------
2800291029602000-----------------
3000311031603210------------------
320033103370-------------------
340035103580-------------------
360037203790-------------------
38003920--------------------
40004120--------------------
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 flangeThe type of sealing face Pressure Class(PN,MPA)
 Plate flange(PL)Raise Face(RF)0.25-2.5
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
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

MaterialFittingsFlangesValvesBolts & Nuts
Carbon SteelA234 Gr WPAA105A216 Gr WCBA193 Gr B7
A194 Gr 2H
A234 Gr WPBA105A216 Gr WCB
A234 Gr WPCA105A216 Gr WCB
Carbon Steel
Alloy
High-Temp
A234 Gr WP1A182 Gr F1A217 Gr WC1A193 Gr B7
A194 Gr 2H
A234 Gr WP11A182 Gr F11A217 Gr WC6
A234 Gr WP12A182 Gr F12A217 Gr WC6
A234 Gr WP22A182 Gr F22A217 Gr WC9
A234 Gr WP5A182 Gr F5A217 Gr C5
A234 Gr WP9A182 Gr F9A217 Gr C12
Carbon Steel
Alloy Low-Temp
A420 Gr WPL6A350 Gr LF2A352 Gr LCBA320 Gr L7
A194 Gr 7
A420 Gr WPL3A350 Gr LF3A352 Gr LC3
Austenitic Stainless SteelA403 Gr WP304A182 Gr F304A182 Gr F304A193 Gr B8
A194 Gr 8
A403 Gr WP316A182 Gr F316A182 Gr F316
A403 Gr WP321A182 Gr F321A182 Gr F321
A403 Gr WP347A182 Gr F347A182 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.TypeCSiSPMnCrNiMoOtheróbósδ5
WP3040.0810.030.045218-208-1151520528
WP304H0.04-0.110.030.045218-208-1151520528
WP304L0.03510.030.045218-208-1348517028
WP304LN0.030.750.030.045218-208-10.5N2:0.1-0.1651520528
WP304N0.080.750.030.045218-208-11N2:0.1-0.1655024028
WP3090.1510.030.045222-2412-1551520528
WP3100.151.50.030.045224-2619-2251520528
WP3160.0810.030.045216-1810-142-351520528
WP316H0.04-0.110.030.045216-1810-142-351520528
WP316LN0.030.750.030.045216-1811-142-3N2:0.1-0.1651520528
WP316L0.03510.030.045216-1810-162-348517028
WP316N0.080.750.030.045216-1811-142-3N2:0.1-0.1655024028
WP3170.0810.030.045218-2011-153-451520528
WP317L0.0310.030.045218-2011-153-451520528
WP3210.0810.030.045217-209-13Ti:5C-0.751520528
WP321H0.04-0.110.030.045217-209-13Ti:4C-0.751520528
WP3470.0810.030.045217-209-13Nb+Ta:10C-1.151520528
WP347H0.04-0.110.030.045217-209-13Nb+Ta:8C-151520528
WP3480.0810.030.045217-209-13Ta:0.151520528
WP348H0.04-0.110.030.045217-209-13Ta:0.151520528
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

GradeUNSTensile Strength, minYield Strength,minElongation min % in 4D
ksiMPaksiMPaLongit %Trans%
ALLALL75515302052820
304LS3040370485251702820
316LS3160370485251702820
304NS3045180550352402820
316NS3165180550352402820
S3172680550352402820
XM-19S20910100690553802820
S3125494-119650-820443002820
S34565115795604152820
S3322873500271852820

 

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.

Delivery

Steel flanges must be packed with seaworthy packing method then delivery to customers, usually the packing way include wooden box, wooden pallet, iron & steel cage, iron & steel pallet etc.

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.

Marking on the flange

Shipping mark stick to outside of package. Following shall be marked on flange body Marking on the flange

  • Manufacturer logo
  • ASTM material code
  • Material Grade
  • Service rating (Pressure-temperature Class))
  • Size
  • Thickness (Schedule)
  • Heat No
  • Special marking if any QT (Quenched and tempered) or W (Repair by welding)

Packing Because of the normal wooden boxes or wooden pallets have to do fumigation treatment, we usually use plywood pallet or plywood case or box to pack steel flanges without fumigation treatment. FF-Flange A105 Accordance with ASME B16.47 Series B Class 150, Thickness 57.15 mm. (2.25")

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FAQ

Q: How long is your delivery time?
A: The delivery time of customized products is generally 25 35 days, and non customized products are generally shipped within 24 hours after payment.

Q: Do you provide samples? Is it free?
A: If the value of the sample is low, we will provide it for free, but the freight needs to be paid by the customer. But for some high value samples, we need to charge a fee.

Q: What are your payment terms?
A: T/T 30% as the deposit,The balance payment is paid in full before shipment

Q: What is the packaging and transportation form?
A: Non steaming wooden box and iron frame packaging. Special packaging is available according to customer needs. The transportation is mainly by sea.

Q: What is your minimum order quantity?
A: There is no minimum order quantity requirement. Customized products are tailor made according to the drawings provided by the customer.