Process Pipeline

Process Pipeline:pipeline connecting fittings, flanges, valves, gaskets, bolts and nuts to meet certain production processes.
Flanges,gaskets, bolts Flanges Threaded flanges
Socket-weld flanges
Slip-on flanges
Lap joint flanges
Weld neck flanges
Blind flanges
Special flanges
Gaskets Spiral wound gaskets
Camprofile gaskets
Metal jacketed gaskets
Bolts Double-headed bolt
Single head bolt


Flange is a part that connects the pipe to the tube and connects to the end of the pipe. Flange connection or flange joint refers to the removable connection of flange, gasket and bolt as a group of combined sealing structures. Pipeline flange refers to the flange used in piping equipment, and in equipment it refers to the import and export flange of equipment. There are holes in the flange, and the bolts connect the flanges tightly. The flanges are sealed with gaskets. The connection between flange and pipeline is divided into threaded connection (wire connection) flange and welding. Welded flanges are commonly used in petrochemical plants.
The international standard of pipe flange has two main systems, namely, European system and American system. In the same system, the standard of pipe flange of different countries can be basically matched with each other.

The flanges of two different systems cannot be matched with each other.

Flange styles can be divided into the following categories:

The type of flange

The type of sealing face

 Pressure Class(PN,MPA)

 Plate flange(PL)

Raise Face(RF)


Flat Face( FF)


Slip on flange(SO)

Raise Face(RF)


Flat Face( FF)


male and female face (MFM)


Tongue and groove face (TG)


Welding Neck Flange(WN)

Raise Face(RF)


male and female face (MFM)


Tongue and groove face (TG)


 Ring Joint Face(RTJ)


Flat Face( FF)


Integral type flange(IF)

Raise Face(RF)


male and female face (MFM)


Tongue and groove face (TG)


 Ring Joint Face(RTJ)


Flat Face( FF)


Socket Weld Flange(SW)

Raise Face(RF)


male and female face (MFM)


Tongue and groove face (TG)


Thread Flange(Th)

Raise Face(RF)


Flat Face( FF)


Lap joint Flange(LP)

Raise Face(RF)


male and female face (MFM)


Tongue and groove face (TG)


Blind flange(BL)

Raise Face(RF)


male and female face (MFM)


Tongue and groove face (TG)


 Ring Joint Face(RTJ)


Flat Face( FF)


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.


The most used flange types in Petro and chemical industry are:

Threaded Flanges

20171125143705 63763 - Process Pipeline

Threaded Flanges are also known as screwed flange, and it is having a thread inside the flange bore which fits on the pipe with matching male thread on the pipe. This type of joint connection is Speedy and simple but not suitable for high presser and temperature applications. Threaded Flanges are mostly used in utility services such as air and water.

Socket-Weld Flanges

20171125143752 46817 - Process Pipeline

Socket-Weld Flanges has a female socket in which pipe is fitted. Fillet welding is done from outside on the pipe. Generally, it is used in small bore piping and only suitable for low pressure and temperature application.

Slip-On Flanges

20171125143828 49905 - Process Pipeline

Slip-On flange has a hole with matching outside diameter of pipe from which pipe can pass. The flange is placed on pipe and fillet welded from both inside and outside. Slip-On Flange is suitable for low pressure and temperature application. This type of flange is available in large size also to connect big bore piping with storage tank nozzles. Normally, these flanges are of forged construction and are provided with the hub. Sometimes, these flanges are fabricated from plates and are not provided with the hub.

Lap Joint Flanges

20171125143911 99176 - Process Pipeline

Lap flange is having two components, a stub end, and a loose backing flange. Stub end is butt welded to the pipe and Backing flange freely move over the pipe. The backing flange can be of different material than stub material and normally of the carbon steel to save the cost. Lap flange is used where frequent dismantling is required, and space is constrained.

Weld Neck Flanges

20171125143951 73458 - Process Pipeline

Weld neck flange are most widely used flanged in process piping. It gives the highest level of joint integrity due to Butt-welded with a pipe. These types of flanges are used in high pressure and temperature application. Weld neck flanges are Bulky & costly with respect to other types of flange.

Blind Flanges

 20171125144049 78663 - Process Pipeline

The blind flange is a blank disc with bolt hole. These types of flanges are used with another type of flange to isolate the piping system or to terminate the piping as an end. Blind flanges are also used as a manhole cover in the vessel.


Except the most used standard flanges, there are still a number of special flanges such as:

  • Orifice Flanges generally come with either Raised Faces or RTJ (Ring Type Joint) facings.
  • Long Weld Neck Flange is normally referred to as the high hub flange.
  • Expander Flange is using a separate reducer-welding neck flange combination.
  • NW Long Weld Neck Flange is a welding neck flange has a very long neck.
  • Spectacle Blind Flange consist of a connected ring (spacer) and a plate (spade).
  • Reducing Flange is used on projects that require the fitting together of different sized pipes.
  • Weldoflange / Nipoflange is a combination of a Welding Neck flange and a supposedly Weldolet or Nipolet.

What is flange face?

The process of flange facing (or flange refacing) involves the machining of flange mating surfaces so that they they produce a tight, leak-proof seal when assembled.

The frequently used term “flange face” refers to the shape of the flange surface area (i.e., the area where the gaskets are positioned and the two mating flanges are tightened). When making a flanged connection, operators should use two flanges with the same type of face, and never mate flanges with different surface areas, such as a flat face with a raised face or a ring joint with a male and female (in this case, the joint would not seal properly and leak).

Industry standards for flange facing
The American Society of Mechanical Engineers (ASME) are the go-to organisation for many standards for mechanical engineering around the world. They have the set the standards to which many engineers work to for flange facing surface finishes.
ASME set the standards for flange face surface finish types through the ANSI accredited ASME Standard B 16.5 ensuring all gasket and flange fittings are consistent and fit for purpose allowing a high quality seal.

Different types of flange faces are used as the contact surfaces to seat the sealing gasket material. ASME B16.5 and B16.47 define various types of flange facings, including the raised face, the large male and female facings which have identical dimensions to provide a relatively large contact area. The ASME B16.5 and ASME B16.47 norms mention a few different types of flange faces:

  • Flat face flange (FF)
  • Raised face flange (RF)
  • Ring joint flange (RTJ)
  • Lap joint flange
  • Male and female flange (M&F)
  • Large and small tongue-and-groove flange (T&G)

flange face - Process Pipeline
Let’s take a closer look at the different types of flange faces, RF, FF, lap joint, ring joint, grooved:


    RF flange finish - Process Pipeline

A raised face flange (RF) is easy to recognize as the gasket surface area is positioned above the bolting line of the flange.

A raised face flange is compatible with a wide range of flange gaskets, ranging from flat to semi-metallic and metallic types (as, for example, jacketed gaskets and spiral wound gaskets), either ring or full face.

The main scope of a raised face flange design is to concentrate the pressure of the two mating flanges on a small surface and increase the strength of the seal.

The height of the raised face depends on the flange pressure rating as defined by the ASME B16.5 specification (for pressure classes 150 and 300, the height is 1.6 mm or 1/16 inch, for classes from 400 to 2500, the raised face height is approximately 6.4 mm, or 1/4 inch).

The most common flange finish for ASME B16.5 RF flanges is 125 to 250 micron Ra (3 to 6 micron Ra). The raised face is, according to ASME B16.5, the default flange face finish for manufacturers (this means that buyer shall specify in the order if another flange face is required, as flat face or ring joint).

Raised face flanges are the most sold type of flange, at least for petrochemical applications.

raised face flange - Process Pipeline


     Flate face flange - Process Pipeline

Flat face flanges (FF) have a contact surface having the same height as the bolting line of the flange. Full face gaskets, generally of the soft type, are used between two flat face flanges.

According to ASME B31.3, a flat face flange should never be mated with a raised face flange as the resulting flanged joint would definitely leak.

flat face flange - Process Pipeline


     Ring joint flange - Process Pipeline

A ring joint flanges (RTJ) is used when a metal-to-metal seal between the mating flanges is required (which is a condition for high-pressure and high-temperature applications, i.e. above 700/800 C°).

A ring joint flange features a circular groove to accommodate a ring joint gasket (oval, or rectangular).

As the two ring joint flanges are bolted together and then tightened, the applied bolting force deforms the gaskets inside the flange groove creating a very tight metal-to-metal seal. To make this happen, the material of the ring joint gasket has to be softer (more ductile) than the material of the flange.

RTJ flanges can be sealed by RTJ gaskets of different styles (R, RX, BX) and profiles (example: octagonal/oval for the R style).

The most common RTJ gasket is the R style with an octagonal section, as it ensures a very strong seal (the oval section is an older type). A “flat groove” design, however, accepts both RTJ gaskets having an octagonal or oval section.

Ring joint flange - Process Pipeline


A lap joint flange has a flat face, which is not used to seal the flanged joint but simply hosts the back of a stub end. The sealing surface is actually on the stub end itself and may be either flat face or raised face.

lap joint and stub ends - Process Pipeline


     Tongue and groove flange - Process Pipeline

Two tongue and groove flanges (T&G face) perfectly fit one into the other: one flange has a raised ring, the other a groove and they can be mated easily (the tongue enters the groove and seals the joint).

Tongue and groove flanges are standardized in both large and small types.


Male and female flange face finish - Process Pipeline

Similarly to tongue and groove flanges, male and female flanges (M&F face type) match one to the other as well.

One flange has an area extended beyond its face area, the male flange, the other flange has a matching depression machined on the facing surface, the female flange.

The female face is 3/16” deep, while the male face is 1/4″ high, and both of them are smooth finished.

The outer diameter of the female face retains the gasket.


To ensure that a flange mates with the gasket and the companion flange perfectly, some roughness is required on the flange surface area (RF and FF flange finish only). The type of roughness on the flange face surface defines the type of “flange face finish”.

Common types are stock, concentric serrated, spiral serrated and smooth flange finish.

Steel flanges are available with four basic face finish, however, the common objective of any type of flange face finish is to create the desired roughness on the face of a flange to ensure a strong match between the flange, the gasket, and the mating flange and thus provide a high-quality seal.

flange face finish - Process Pipeline

Source: Officine Orsi, Italy (

Let’s now dive into the most common flange face finish types:


The stock finish is the most widespread type of finish as it suits the large majority of applications. The pressure embeds the soft face of the gasket into the flange finish and results in the formation of a good seal due to the friction existing between the contacting parts.

As the mating flanges are bolted together, gaskets get “squeezed” into the flange face surface and create a very tight seal.

A stock finish face is manufactured using a phonographic spiral groove featuring a 1.6mm radius round-nose tool with a depth of 0.15mm and a feed-rate of 0.8mm per revolution. The resulting “Ra” value (AARH) for the surface ranges from 125µinch to 500 µinch (125 µm to 12.5 µm).


Spiral serrated finish is a phonographic spiral groove type that differs from the stock finish as the groove is crafted by a 90 degrees tool (instead of a round nosed one) that creates a “V” geometry with a 45-degree serration angle.

A serrated finish, concentric or spiral, has from 30 to 55 grooves per inch and roughness between 125 to 250 µinch.


The concentric serrated flange finish features concentric grooves instead of spirals.

The grooves are crafted by the same 90-degree tool used for the spiral serrated finish, but the serrations have an even design on the face of the flange. To have concentric grooves, the tool has a feed rate of 0.039mm per revolution and a depth of 0.079mm.


Flanges with a smooth finish do not show visible tool markings at naked eye.

This type of flange finish is used with metal-facing gaskets such as the jacketed type.

As per the stock finish, this is achieved by having the contact surface machined with a continuous spiral groove generated by a 0.8mm radius round-nosed tool at a feed rate of 0.3mm per revolution with a depth of 0.05mm (that creates a roughness between Ra 3.2 and 6.3 micrometers, i.e. 125 – 250 microinches).


The cold water finishes appear shiny to the naked eye and very smooth. The AARH value for these surfaces ranges between 85 µinch to 100 µinch. They are used with metal to metal seals (no gasket).

flange face finish - Process Pipeline


The term AARH (“arithmetic average roughness height”) refers to the flange face smoothness/roughness. The average arithmetic roughness height values are very important during the selection of flanges and gasket materials. Higher the “Ra” values depict a more rough surface, while lower values represent the smoother surface.

Every material possesses a surface roughness and sometimes surfaces are finished deliberately to have a specific roughness (small or bigger).

The “Arithmetic Average Roughness Height” (AARH) is the common indicator to measure the roughness of a surface, and it is the average height of the irregularities on the metal surface, from the mean line as shown in the following figure.

The symbol Y1 to Y8 represent the peak heights which are measured from the mean line.

Arithmetic Average Roughness Height is usually measured in micro-inches and denoted by symbol “Ra”.

There are various standards for the roughness of surfaces, set according to their type of application. The equipment used to measure the surface roughness is the so-called “profilometer” (which are available in the contact and non-contact types).

In contact type profilometer the roughness is measured by moving the material under the profilometer stylus. However, modern equipment features non-contact measurements, leveraging the optical and ultrasonic technologies.


ASME/ANSI defined specific roughness standards for the flanges, as the flange face finish plays a pivotal role in gasket’s reliability and service life.
According to the ASME/ANSI specifications, the serrated, spiral serrated, and concentric flange face finish should have an average roughness of 125 µinch to 250 µinch (3.2 µm to 6.3 µm).

The tool used to imprint a rough finish on the flange should have a radius of 0.06 inch (1.5mm) or larger. The groove density on the flange face should be from 45 grooves per inch to 55 grooves per inch (1.8 grooves/ mm. to 2.2 grooves/ mm.).

These are the standards for semi-metallic and nonmetallic gaskets. If the average roughness of flange face is not according to the described standards, the contacting surfaces would not properly seal and the flanged joint may wear after some time working under pressure (resulting in loss of bolt joint tightness and a possible leakage).

The soft nonmetallic materials such as PTFE may be used for more comfortable facing and better creep resistance.


The sealing performance of the flanges’ gaskets depends on the AARH, the flange dimensions and the pressure of the stud bolts. According to ASME, the adjacent imperfections should be separated by a distance of at least 4 times the maximum radial projection.

The radial projection can be evaluated by subtracting the inner radius from the outer radius.

The serrations shall be at the same level, and the protrusion above them is not permitted. It can cause the adjacent serrations to lose hold of the gasket material and may result in wears and leakages.


Flange gasket

What is a Flange Gasket?

Flange gaskets are used to create a static seal between two flanges faces, at various operating conditions, with varied pressure and temperature ratings. A gaskets fills the microscopic spaces and irregularities of the flange faces, and then it forms a seal that is designed to keep liquids and gases. Correct installation of damage-free gaskets and demage-free flange faces is a requirement for a leak-free flange connection.

Types of gaskets

Materials for gaskets can be divided into three main categories:


NON-METALLIC GASKETS are usually composite sheet materials are used with flat-face and raised-face flanges in low Pressure Class applications. Non-metallic gaskets are manufactured from arimid fiber, glass fiber, elastomer, Teflon® (PTFE), graphite etc.. Full-face gasket types are suitable for use with flat-face flanges. Flat-ring gasket types are suitable for use with raised face flanges.

ASME B16.21 covers types, sizes, materials, dimensions, dimensional tolerances, and markings for non-metallic flat gaskets.

Click the image for a larger size

non metallic gaskets - Process Pipeline

Image comes from:

SEMI-METALLIC GASKETS are composites of metal and non-metallic materials. The metal is intended to offer strength and resiliency, while the non-metallic portion provides conformability and sealability. Often used semi-metallic gaskets are spiral wound and camprofile, and a variety of metal-reinforced graphite gaskets.

Semi-metallic are designed for almost all operating conditions and high-temperature and pressure applications, and are used on raised face, male-and-female, and tongue-and-groove flanges.

ASME B16.20 covers materials, dimensions, dimensional tolerances, and markings for metallic and semi-metallic gaskets.

Typical Spiral Wound gasket

gasket spiral wound - Process Pipeline

METALLIC GASKETS are fabricated from one or a combination of metals to the desired shape and size. Often used metallic gaskets are ring-type-joint gaskets (RTJ). They are always applied to special, accompanying flanges which ensure good, reliable sealing with the correct choice of profiles and material.

Ring Type Joint gaskets are designed to seal by “initial line contact” or wedging action between the mating flange and the gasket. By applying pressure on the seal interface through bolt force, the “softer” metal of the gasket flows into the microfine structure of the harder flange material, and creating a very tight and efficient seal.

ASME B16.20 covers materials, dimensions, dimensional tolerances, and markings for metallic and semi-metallic gaskets.

gasket rtj - Process Pipeline

Typical RTJ gaskets

Often used Semi-Metallic gaskets

Here below you will find a short description of a number of semi-metallic gaskets, which are largely used.

Spiral Wound gaskets

The concept of spiral wound gasket construction was originated by Flexitallic in 1912, inaugurating the beginning of a new era in safe, effective sealing. The primary purpose for this development was the increasingly severe temperatures and pressures used by U.S. refinery operators in the first half of the century.

The necessity for a gasket to have the ability to recover cannot be over emphasized. The effects of pressure and temperature fluctuations, the temperature differential across the flange face, together with bolt stress relaxation and creep, demand a gasket with adequate flexibility and recovery to maintain a seal even under these varying service conditions. The Spiral Wound Gasket is the precision engineered solution to such problems, meeting the most exacting conditions of both temperature and pressure in flanged joints and similar assemblies and against virtually every known corrosive and toxic media.The spiral wound gasket meets the most exacting conditions of both temperature and pressure in flanged joints and similar assemblies and against every known corrosive and toxic media.

The spiral wound gasket depends upon the mechanical characteristics of a formed metal spiral strip, rather than the compressive virtues of more traditional gasket materials. This makes it particularly suitable for low or fluctuating bolt loads. The sealing strips, or fillers, are usually graphite, although other materials such as Teflon® (PTFE) may be used, the windings are always stainless steel. For this type of gasket to work the spiral must not be over compressed, hence one of two types of compression control is usually used.

The completed gasket is fitted into a steel ring of specific thickness. When the gasket is fitted into a flange and the bolt load is applied, flange closure is governed by the outer steel ring of the gasket. To further improve the pressure rating of the spiral wound gasket, a steel ring may be added to the inside. This gives an additional compression limiting stop and provides a heat and corrosion barrier protecting gasket windings and preventing flange erosion. It is customary to select inner ring material to be the same as the metal winding.

ASME B16.20 which covers spiral wound gaskets requires the use of solid metal inner rings in: Pressure Class 900, nominal pipe sizes 24 and larger, Pressure Class 1500 from nominal pipe sizes 12 and larger, Pressure Class 2500 from nominal pipe sizes 4 and larger and all PTFE filled gaskets. In the same standard is also described how a spiral wound gasket should be characterized, below you will find a image on it.

Marking Spiral Wound Gaskets

gasket sw marking - Process Pipeline


Cross Section of a Spiral Wound gasket
Click the image for a larger size

spw - Process Pipeline

Camprofile gaskets

Camprofile or “Grooved” gaskets have proven themselves in all industrial applications. Camprofile gaskets are found in industrial power plants and in the primary circuits in nuclear installations. Used either between flanges or in Heat Exchanger units in nuclear applications. The Petro and chemical industry benefit too, as the gaskets are used in applications where high pressures and temperatures are maintained and consequently high bolt loads need to be controlled.

camprofile - Process Pipeline

Camprofile gaskets consist of a metal core (generally Stainless Steel) with concentric grooves on either side with sealing materials. The sealing layers (depending on the service duty) can be Graphite, PTFE (Teflon®), CAF or Metal (e.g. Aluminium or Silver). Camprofile’s can be used without sealing layers to provide an excellent seal but there is a risk of flange surface damage – especially at high seating loads. The sealing layers protect the flange surfaces from damage in addition to providing an effective seal.

Metal Jacketed gaskets

Metal Jacketed gaskets, as the name suggests, are comprised of a metallic outer shell with either a metallic or non-metallic filler. The filler material gives the gasket resilience, while the metal jacket protects the filler and resists pressures, temperatures and corrosion.

metal jacketed gasket - Process Pipeline

They are traditionally used for Heat Exchanger applications, pumps and Valves, however the resilience and recovery properties of these gaskets are limited. Metal Jacketed gaskets require smooth flange surface finishes, high bolt loads and flange flatness in order to seal effectively.

There are many different styles of jacketed gaskets available. In the main Menu “Gaskets” you will find a link to the dimensions of double jacketed flange gaskets. In that type the filler material is completely enclosed by a two piece metal jacket, which covers both the inside and outside diameters and both contact surfaces.

Metallic gaskets for RTJ Flanges

The ring type joint was initially developed for use in the petroleum industry, where high pressure/temperature applicationsnecessitated the need for a high integrity seal. They are mainly used in the oil field on drilling and completion equipment. Ring type joints are also commonly used on Valves and pipework assemblies, along with some high integrity pressure vessel joints.

Most applied type is style R ring that is machined to tight manufacturing tolerances in accordance with the relevant standards, to ensure correct installation in standard API 6B and ASME B16.5 Ring Type Flanges.
Oval and Octagonal RTJ’s with the same ring size designation can be interchangeable in standard flanges with flat bottomed ring grooves. For the old style round bottomed grooves Oval RTJ’s only can be used. Materials of construction are selected to match the flange material and to be resistant to the corrosive and erosive media. In addition, the material hardness of the RTJ’s is less than the hardness of the flanges to ensure the RTJ is deformed and not the flanges when assembled. Non-standard size RTJ’s are specifically designed to be installed in flanges designed around a specific application rather than a standard flange.

rtj styleR - Process Pipeline
rtj styleRX - Process Pipeline
rtj styleBX - Process Pipeline


Oval and Octagonal RTJ’s are designed to seal pressures of up to 6,250 psi in accordance with ASME B16.20 and up to 5,000 psi in accordance with API 6A pressure ratings. Typical high pressure and temperature applications where these gaskets are used include Valve and pipe-work assemblies in oil field drilling and refining applications. In addition, these gaskets are installed in high pressure vessels and pumps.


Under axial compressive load, ring type joints plastically deform and flow into the irregularities of the flange groove. Since the load bearing area of the ring type joint is relatively small, very high surface stresses result between the sealing faces of the ring type joint and the groove. These stresses are further increased on the Style RX and BX rings which allows very high internal pressures to be sealed. Since ring type joints are solid metal, their recovery characteristics are poor. The seal is maintained by the action of axial load upon the gasket.


Ring type joints are designed to have a limited amount of positive interference, which ensures that the ring type joint seats correctly into the groove on compression. Their reuse is not recommended for two reasons:
1. The initial seating of the gasket will be impaired
2. When the gasket is plastically deformed, work hardening of the external metal surface occurs. This may result in permanent damage to the groove.


On compression of the flange assembly, it is imperative that the ring type joint be significantly softer than the flange groove so that the gasket plastically deforms and not the groove. The use of harder ring type joints can result in flange groove damage. For this reason, ring type joints are supplied with the following maximum hardness values:

  Maximum Hardness  


Wst No Brinel (1) HRB (2) ID

Soft Iron

  90 56 D

Low Carbon Steel

  120 68 S

4 – 6% Chrome
1/2% Moly

  130 72 F5

Type 304
Stainless Steel

1.4301 160 83 S304

Type 316
Stainless Steel

1.4401 160 83 S316

Type 347
Stainless Steel

1.4550 160 83 S347

Type 410
Stainless Steel

1.4006 170 96 S410


(1) Measured with 3000 kg load except soft iron which is measured with 500 kg load.

(2) (Rockwell) measured with 100 kg load and 1/16in diameter ball.

Source: Werner Sölken

Bolts for flanges

Bolts used to connect flanges are single-head bolts and double-head bolts, whose threads are generally triangular metric thick threads.
Europium single head bolt
Single head bolt is also called hexagonal head bolt. Single-head bolt is divided into semi-refined and refined two kinds, in low and medium pressure process pipelines, the most used is semi-refined single-head bolt.
The commonly used materials for manufacturing single head bolts are Q235A, No. 35 steel and 25Cr2MoVA. It is often used for flange connection under nominal pressure of 2.5 MPa.
The applicable temperature depends on the bolt material. For example, the applicable temperature of the bolt made of No. 35 steel can reach 350 and that made of 25Cr2MoVA steel can reach 570.

20190725013105 99598 - Process Pipeline
Single head bolt

20190725013250 61712 - Process Pipeline
Isometric double-headed bolt
Europium double head bolt

20190725013609 26185 - Process Pipeline
Most of the double-headed bolts used in the process pipeline are refined bolts with equal length and double-headed. It is suitable for flange connection with high temperature and pressure.
The materials are 35 steel, 30CrMoA, 35CrMoA, 25Cr2MoVA, 0Cr19Ni9, 0Cr15Ni25Ti2MoAlVB and 37SiMn2MoVA. The nominal pressure ranges from 1.6 MPa to 32.0 MPa, and the applicable temperature can reach 700 C.
Nuts, collectively known as hexagonal nuts. There are two kinds: semi-refined and refined. According to the structure of the nut, it can be divided into two types: A type and B type.
Semi-refined single-head bolts mostly use type A nuts; refined double-head bolts mostly use type B nuts. Nuts and bolts should be used together, but the hardness of the material used for making nuts should not exceed the hardness of the material used for bolts.
20190725013901 52272 - Process Pipeline
Hexagonal Nut Diagram

Source: China Process Pipeline Manufacturer – Yaang Pipe Industry Co., Limited (

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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process pipeline - Process Pipeline
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Process Pipeline:Pipeline connecting fittings, flanges, valves, gaskets, bolts and nuts to meet certain production processes.
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