Long Radius Elbow: Enhancing Fluid Flow in Piping Systems

Chemical Composition (%) of ASTM A420

Notes:

*For grade WPL6, the limit for Columbium may be increased up to 0.05% on heat analysis and 0.06% on product analysis.

*Fittings of WPL3 made from plate or forgings may have 0.90 % max manganese.

*Fittings of WPL8 made from plate may have 0.98 % max manganese.

Mechanical properties of ASTM A420

*All the elongation values are on the basis of standard round specimen, or small proportional specimen, min % in 4 D.

ASTM A234 is Standard Specification for steel pipe fittings includes carbon and alloy steel material for moderate and high temperature services.

Types of Elbows based on Direction Angle

According to fluid flow direction of the pipes, elbows can be divided into different degrees, such as 45 degree, 90 degree, 180 degree, which are most common elbows. Also there are 60 degree and 120 degree elbows for some special pipelines. This degree is just an representation of the angle by which the fluid flow is going to change after flowing through the said elbow.

Types of Elbows based on Length and Radius

Elbows are split into two groups which define the distance over which the flowing fluid change direction; the center line of one end to the opposite face. This is known as the “Center to Face” distance and is equivalent to the radius through which the elbow is bent.

If the radius is the same as pipe diameter (Center-to-Face dimension of 1.0 X diameter ), it called Short Radius Elbow (SR elbow) used normally for low pressure and low speed pipelines or in tight areas where clearance is the main issue. If the radius is larger than pipe diameter (Center-to-Face dimension of 1.5 X diameter) then we call it a Long Radius Elbow (LR Elbow) used for high pressure and high flow rate pipelines.

Long Radius Elbow VS Short Radius Elbow

The elbow is divided into its radius of curvature and can be divided into a long radius elbow and a short radius elbow. The long radius elbow refers to the outer diameter of the tube whose radius of curvature is equal to 1.5 times, that is, R = 1.5D. A short radius elbow means that its radius of curvature is equal to the outer diameter of the tube, ie R = D. Where D is the diameter of the elbow and R is the radius of curvature. Normal use of the length of the radius Sometimes to reduce the loss of resistance or elbow wear, the elbow with a larger bending radius will be used (in fact, it is not called elbow); when there is a limit on the installation position, a short radius elbow will be used.

When to choose a long radius elbow or a short radius elbow?

There are two types of pipe sizes for process installation, namely pipe outer diameter and nominal size. D, DN, refers to the nominal size of the pipe. It does not represent the inner diameter of the pipe or the outer diameter of the pipe. It is a nominal size designed and used. The elbow is the elbow, and the manufacturing method is divided into the push elbow, the extrusion elbow and the welded miter elbow. The structure length is 1.0D, 1.5D, 2.0D.

At present, there are two kinds of norms implemented in this area in China: metric and imperial. For example: 1.5D steel seamless elbow, DN100 outer diameter ¢108 and ¢114.3, actual structural length L152, DN200 outer diameter ¢219 and ¢216.3, actual structural length L302. In use, long radius elbow (R = 15DN): in general, should be preferred; short radius elbow (R = 1.0DN): mostly used in applications where size is limited. Its high working pressure should not exceed 0.8 times of the long radius elbow of the same specification.

Elbow (R=nDN): used to moderate the scouring and kinetic energy of the media at the bend, available to R=3DN, 6DN, 10DN, 20DN. According to different manufacturing methods, it is divided into push elbow, extrusion elbow and welded miter elbow.

Pushing elbows and extrusion elbows: Commonly used for welding mitered elbows on medium and small-sized pipes with strict media conditions: It is often used on large-sized pipes with moderate media conditions, and the bending radius is not to be less than its nominal diameter. 1.5 times. When the miter angle of the miter elbow is greater than 450, it should not be used on highly toxic, flammable medium pipes, or on pipes subjected to mechanical vibration, pressure pulsation and alternating load due to temperature changes.

So how do we buy qualified elbows? Detecting the back arc of the elbow: Seamless elbow detection of the thickness of the back arc is an important task. Many large pipe elbow manufacturers or strict engineering inspection of the back arc is a must. It is related to the safety and stability of the pipeline operation.

Everyone knows that both the seamless steel pipe and the seamless elbow are under pressure, that is, the pressure is very large when running. Under normal circumstances, the safety factor of the thickness of the seamless elbow designed and installed is about six times. For example, the 219*8 seamless elbow, the pipeline medium is ordinary water, the temperature is usually not higher than one hundred degrees Celsius, and the pressure required to blast such a seamless elbow is about 300 kg, that is to say, The pressure inside the pipeline needs to reach PN30, and the seamless elbow will be blasted, and the operating pressure of this elbow is probably about it. It is estimated that the maximum will not exceed PN6.4, which is generally around PN4.0, of course. With the corrosion of the pipeline, the seamless elbow will also be corroded to varying degrees. In order to ensure its safe operation, the necessity of overhaul is also great.

The current process of making seamless elbows will lead to the phenomenon of back arc thinning. Under normal circumstances, the wall thickness of the mouth will be about two millimeters thinner than the back arc. The common thickness and pressure are not thinner even if the back arc is thinned. There will be too many safety hazards, because the elbow has not been replaced until the elbow has a dangerous accident. But as a rigorous project, what is not the same, and the medium inside the pipeline is also responsible, not just water. There may be oil or other impurities, the temperature is high and the pressure is high, and the thickness of the back arc as the weak place determines the life of the seamless elbow. Therefore, the importance of detecting the back arc is naturally great. With the thickness gauge, read the thickness of a point at the elbow directly.

What does Short Radius (SR) or Long Radius (LR) means?

You will often hear SR45 elbow or LR45 elbow. The 45 or 90 refers to the angle of the bend for buttweld fitting to change the direction of flow. A long radius elbow (LR 90 Elbow or LR 45 elbow) will have a pipe bend that will be 1.5 times the size of the pipe. So, a 6 inch LR 90 has bending radius that is 1.5 x nominal pipe size. A short radius elbow (SR45 or SR90) has a pipe bend that is equal to the size of the fitting, so a 6” SR 45 has a bending radius that is 6” nominal pipe size.

What is a 3R or 3D elbow pipe fitting?

First, the terms 3R or 3D are used synonymously. A 3R butt weld elbow has a bending radius that is 3 times the nominal pipe size. A 3R elbow is smoother than SR or LR fitting.

Types of Elbows based on Connection with Pipe

As per the connection with pipe, elbows could be classified as Butt Welded Elbow, Socket Welded Elbow and Threaded Elbow.

Butt Welded Elbow

Butt weld elbow is a steel elbow formed by hot pressing or forging. Its connection form is to directly weld the elbow and steel pipe. Butt welded elbows have beveled ends to allow for ease of welding. This bevel allows for full penetration weld in most of the cases. Butt welded elbows are mainly used for elbow with higher pressure and temperature.

Socket Welded Elbow

Socket weld elbow is also welded to the pipe and fittings end. Unlike the butt weld elbow, the socket weld elbow has a trapezoidal area at the end. We can insert pipe end into this area (the diameter of SW elbow is matched with the outer diameter of pipe), then do welding work to connect them together. Therefore, the actual diameter of SW elbow end is greater than the elbow diameter.

Threaded Elbow

The shape of threaded elbow is similar to the SW elbow, except that the inner surface of the trapezoidal area has been machined into thread. It is easier to install and remove, good for pipeline repair and maintenance.

Types of Elbows based on Material of Construction

Stainless Steel Elbow : ASTM A403 WP Gr. 304, 304H, 309, 310, 316, 316L, 317L, 321, 347, 904L
Carbon Steel Elbow : ASTM A 234 WPB , WPBW, WPHY 42, WPHY 46, WPHY 52, WPH 60, WPHY 65 & WPHY 70.
Low Temperature Carbon Steel Elbow : ASTM A420 WPL3, A420 WPL6
Alloy Steel Elbow : ASTM / ASME A/SA 234 Gr. WP 1, WP 5, WP 9, WP 11, WP 12, WP 22, WP 91
Duplex Steel Elbow : ASTM A 815, ASME SA 815 UNS NO S31803, S32205. Werkstoff No. 1.4462
Nickel Alloy Elbow : ASTM / ASME SB 336 UNS 2200 ( NICKEL 200 ), UNS 2201 (NICKEL 201 ), UNS 4400 (MONEL 400 ), UNS 8020 ( ALLOY 20 / 20 CB 3, UNS 8825 INCONEL (825), UNS 6600 (INCONEL 600 ), UNS 6601 ( INCONEL 601 ), UNS 6625 (INCONEL 625), UNS 10276 ( HASTELLOY C 276 )

Some Other Types of Elbows

In addition to the above defined elbows there are few more types of elbows which are not used on regular basis. Few of them has been defined below.

Reducing Elbow

A reducing elbow is a type of fitting which is used to join two pipes of different sizes. The reducing elbow is so called because it looks like a reducing piece and elbow combined into one. The reducing elbow eliminates one pipe fitting (reducer) and reduces the welding by more than one-third. Also, the gradual reduction in diameter throughout the arc of the reducing elbow provides lower resistance to flow and reduces the effect of stream turbulence and potential internal erosion. These features prevent sizable pressure drops in the line.

For many suppliers it is a non standard item resulting into high price with a long delivery time. The use of a “normal” elbow with a separate reducer is an option if the situation allows.

Male Pipe Elbows & Female Pipe Elbows

Male pipe elbows and female pipe elbows are popular tube fittings which provide an fluid flow directional change of a tubing run. While a male pipe elbow is used to connect fractional tube to female tapered pipe thread, a female elbow is used to connect fractional tube to male NPT thread. These types of tube fittings like male elbows and female elbows have been specifically designed for use on instrumentation, process and control systems and equipment employed in chemical, petroleum, fluid power, electronic and pulp and paper plants.

Wall Thickness of Elbows

The weakest point on an elbow is the inside radius. ASME B16.9 only standardizes the center to face dimensions and some “squareness” dimensional tolerances. The wall thickness at the weld line location even is standardized, but not through the rest of an elbow. The standard states that the minimum tolerance will be within 12.5% of the minimum ordered wall thickness of the pipe. A maximum tolerance is specified only at the ends of the fitting. Many providers of butt weld elbows provide one schedule greater thickness so that sufficient wall thickness, after forming, remains.

How to purchase pipe elbows?

Pipe elbow fittings is a very important pipe fitting. When we talk about a pipe elbow, it means a length of pipe with a sharp bend in it. Pipe elbows are fitting accessories which are used widely in various industrial sectors in pipe fitting. A pipe elbow is frequently used in pressurized applications and are available in various shapes and sizes for use in different applications. A pipe elbow is a fitting installed between two lengths of pipe or tube allowing a change of direction, usually in the 90° or 45° direction.

Certain factors are to be considered for the proper purchase of pipe elbows. These factors are:

• Materials
• Size
• Standard type
• Threaded type
• Maximum assurance of reliable performance in-
  • High pressure
  • High impulse
  • High vacuum
  • High vibration
  • High temperature

Everyone knows that both the pipeline and the seamless elbow are under pressure, that is, the pressure is very large when running. Under normal circumstances, the safety factor of the thickness of the seamless elbow designed and installed is about six times. For example, the 219*8 seamless elbow, the pipeline medium is ordinary water, the temperature is usually not higher than one hundred degrees Celsius, and the pressure required to blast such a seamless elbow is about 300 kg, that is, The pressure inside the pipeline needs to reach PN30, and the seamless elbow will be blasted, and the operating pressure of this elbow is probably about it. It is estimated that the maximum will not exceed PN6.4, which is generally around PN4.0, of course. With the corrosion of the pipeline, the seamless elbow will also be corroded to varying degrees. In order to ensure its safe operation, the necessity of overhaul is great.

The current process of making seamless elbows will lead to the phenomenon of back arc thinning. Under normal circumstances, the wall thickness of the mouth will be about two millimeters thinner than the back arc. The common thickness and pressure will not be thin even if the back arc is thinned. There are too many safety hazards, because the elbow has not been replaced until the elbow has a dangerous accident. But as a rigorous project, what is not the same, and the medium inside the pipeline is also responsible, not just water. There may be oil or other impurities, the temperature is high and the pressure is high, and the thickness of the back arc as the weak place determines the life of the seamless elbow. Therefore, the importance of detecting the back arc is naturally great. With a thickness gauge, read the thickness of a point at the elbow directly.

Detect the inner and outer diameters of the elbow: For example, the outer diameter dimension D of the elbow is detected: the data of the upper limit and the lower limit are referenced, and the actually measured outer diameter of the product is qualified between the upper and lower limits, and the unqualified product is outside the upper or lower limit range.

Detect the wall thickness of the elbow: use the thickness gauge to directly read the thickness of the thinnest part of the elbow.

Detect the center height of the elbow: first measure the length of the outer circle of the elbow. Using this length value /1.57, the value obtained by subtracting half of the diameter of the elbow is the center height of the elbow.

Detecting the weight of the elbow: The elbow is made of steel pipe. We only know the weight of the elbow when the elbow is cut, and the size of the elbow and the back arc of the elbow. The dimensions are basically the same. Let’s calculate the length of the back arc of the elbow: the diameter of the elbow is D, the radius of curvature is 1.5D, and the length of the back arc of the elbow is (1.5+0.5)*D*2*3.14/4 Simplification we can get, 1.5 times elbow back arc length L = D * 3.14. This is only an estimate. The value of the Chinese standard is slightly smaller than this value. After the length of the back arc is L, the weight of the steel pipe is calculated by the calculation formula of the steel pipe: (Da)*a*0.02466*L/1000, ( a is the wall thickness of the elbow), the unit of this weight is KG, so we can get the weight of the carbon steel elbow. If it is a stainless steel elbow, just replace 0.02466 with 0.02491. The calculated theoretical weight is then compared to the actual weight.

Radiographic inspection of elbows: Radiographic inspection detects volumetric defects of elbows, such as pores, slag inclusions, shrinkage cavities, and looseness.

Wall Thickness of Elbows

The weakest point on an elbow is the inside radius. ASME B16.9 only standardizes the center to face dimensions and some "squareness" dimensional tolerances. The wall thickness at the weld line location even is standardized, but not through the rest of an elbow. The standard states that the minimum tolerance will be within 12.5% of the minimum ordered wall thickness of the pipe. A maximum tolerance is specified only at the ends of the fitting.

Many providers of buttweld elbows (and tees) provide one schedule greater thickness so that sufficient wall thickness, after forming, remains.

Steel Pipe Elbow Coating

Along with build quality, the longevity and reliability of steel pipe elbows are highly dependent on the type and quality of the coating used. However, applying coatings to pipe elbows is not just about preventing corrosion, but can affect the evenness of flow through the pipe and the need to prevent contamination of pipe contents ((e.g. foodstuffs or drinking water). We offer corrosion resistance coating service for steel pipe elbow, our coating service includes light oiling, black painting, FBE coating, 2 layers or 3 layers PE coating, hot-dip galvanizing.

ASME / ANSI B16.9 dimension

ASME B16.9 Standard covers overall dimensions, tolerances,ratings, testing, and markings for factory-made wrought buttwelding fittings in sizes NPS 1⁄2 through NPS 48 (DN 15 through DN 1200).

Tolerances of Welded Fittings

All dimensions are given in inches. Tolerances are equal plus and minus except as noted.

1. Out-of-round is the sum of absolute values of plus and minus tolerance.
2. This tolerance may not apply in localized areas of formed fittings where increased wall thickness is required to meet design requirements of ASME B16.9.
3. The inside diameter and the nominal wall thicknesses at ends are to be specified by the purchaser.
4. Unless otherwise specified by the purchaser, these tolerances apply to the nominal inside diameter, which equals the difference between the nominal outside diameter and twice the nominal wall thickness.

The ASME B16.9 pipe fittings can be used under the jurisdiction of the ASME Boiler & Pressure Vessel Code (BPVC) as well as the ASME Code for pressure piping. Referencing pressure ratings of flanges per ASME B16.5, they can be designated as Classes 150, 300, 600, 900, 1500 and 2500. The allowable pressure ratings for ASME B16.9 pipe fittings may be calculated as for straight seamless pipe of equivalent material in accordance with the rules established in the applicable sections of ASME B31 Code for pressure piping.

Design of Fittings

The design of butt welding pipe fittings made to ASME B16.9 shall be established by one of the following methods: (a) mathematical analyses contained in pressure vessel or piping codes; (b) proof testing; (c) experimental stress analysis with hydrostatic testing to validate experimental results; (d) detailed stress analysis with results evaluation.

Standard Marking

Generally, ASME B16.9 pipe fittings shall be marked to show the following details: “trademark + material grade + wall thickness + size + heat number”. For example, “M ASTM A234 WP5 SCH80 6″ 385“. When steel stamps are used, care shall be taken so that
the marking is not deep enough or sharp enough to cause cracks or to reduce the wall thickness of the fitting below the minimum allowed.

Material & Manufacture

The ASME B16.9 fittings may be made from an extensive range of mateirals covering (1) carbon and low-alloy steels in accordance with ASTM A234 and ASTM A420; (2) austenitic and duplex stainless steels in accordance with ASTM A403 and ASTM A815; (3) nickel alloys in accordance with ASTM B366; (4) aluminum alloys in accordance with ASTM B361; and (5) titanium alloys in accordance with ASTM B363.

Pipe Fittings Dimensions Tolerance as per ASME B16.9:

Sizes 1/2″ – 48″

• ASME / ANSI B16.9 Butt Weld Elbow – Long Radius
• ASME / ANSI B16.9 Butt Weld Elbow – Short Radius
• ASME / ANSI B16.9 Butt Weld Reducing Elbow
• ASME / ANSI B16.9 Butt Weld 45° Elbow
• ASME / ANSI B16.9 Butt Weld Fabricated Tee
• ASME / ANSI B16.9 Butt Weld Reducer
• ASME / ANSI B16.9 Butt Weld Concentric Reducer
• ASME / ANSI B16.9 Butt Weld Eccentric Reducer
• ASME / ANSI B16.9 Butt Weld 3D Elbow
• ASME / ANSI B16.9 Butt Weld Stub Ends
• ASME / ANSI B16.9 Butt Weld Cross
• ASME / ANSI B16.9 Butt Weld Reducing Cross
• ASME / ANSI B16.9 Butt Weld Tees
• ASME / ANSI B16.9 Butt Weld End Cap
• ASME / ANSI B16.9 Butt Weld Coupling
• ASME / ANSI B16.9 Butt Weld Pipe Nipple
• ASME / ANSI B16.9 Butt Weld 5D Elbow
• ASME / ANSI B16.9 Butt Welded Pipe Fittings

Standard

Pipe fitting dimensions are in either metric or Standard English.

Because pipe fitting covers Pipe Fitting Dimensions several aspects, only the most common pipe fitting sizes can be given here. The most applied version is the 90° long radius and the 45° elbow, while the 90° short radius elbow is applied if there is too little space. The function of a 180° elbow is to change direction of flow through 180°. Both, the LR and the SR types have a center to center dimension double the matching 90° elbows. These fittings will generally be used in furnesses or other heating or cooling units.

Some of the standards that apply to buttwelded fittings are listed below. Many organizations such as ASME, ASTM, ISO, MSS, etc. have very well developed standards and specifications for buttwelded fittings. It is always up to the designer to ensure that they are following the applicable standard and company specification, if available, during the design process.

Some widely used pipe fitting standards are as follows:

ASME: American Society for Mechanical Engineers
This is one of the reputed organizations in the world developing codes and standards.
The schedule number for pipe fitting starts from ASME/ANSI B16. The various classifications of ASME/ANSI B16 standards for different pipe fittings are as follows:

• ASME/ANSI B16.1 – 1998 – Cast Iron Pipe Flanges and Flanged Fittings
• ASME/ANSI B16.3 – 1998 – Malleable Iron Threaded Fittings
• ASME/ANSI B16.4 – 1998 – Cast Iron Threaded Fittings
• ASME/ANSI B16.5 – 1996 – Pipe Flanges and Flanged Fittings
• ASME/ANSI B16.11 – 2001 – Forged Steel Fittings, Socket-Welding and Threaded
• ASME/ANSI B16.14 – 1991 – Ferrous Pipe Plugs, Bushings and Locknuts with Pipe Threads
• ASME/ANSI B16.15 – 1985 (R1994) – Cast Bronze Threaded Fittings
• ASME/ANSI B16.25 – 1997 – Buttwelding Ends
• ASME/ANSI B16.36 – 1996 – Orifice Flanges etc.

ASTM International: American Society for Testing and Materials
This is one of the largest voluntary standards development organizations in the world. It was originally known as the American Society for Testing and Materials (ASTM).

• ASTM A105/A105M – Specification for Carbon Steel Forgings for Piping Applications
• ASTM A234/A234M – Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service
• ASTM A403/A403M – Specification for Wrought Austenitic Stainless Steel Piping Fittings
• ASTM A420/A420M – Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Low-Temperature Service

AWWA: American Water Works Association

AWWA About – Established in 1881, the American Water Works Association is the largest nonprofit, scientific and educational association dedicated to managing and treating water, the world’s most important resource.

• AWWA C110 – Ductile-Iron and Gray-Iron Fittings, 3 Inch Through 48 Inch (75 mm Through 1200 mm), for Water and Other Liquids
• AWWA C208 – Dimensions for Fabricated Steel Water Pipe Fittings

ANSI: The American National Standards Institute

ANSI is a private, non-profit organization. Its main function is to administer and coordinate the U.S. voluntary standardization and conformity assessment system. It provides a forum for development of American national standards. ANSI assigns “schedule numbers”. These numbers classify wall thicknesses for different pressure uses.

MSS STANDARDS: Manufacturers Standardization Society
The Manufacturers Standardization Society (MSS) of the Valve and Fittings Industry is a non-profit technical association organized for development and improvement of industry, national and international codes and standards for: Valves, Valve Actuators, Valve Modification, Pipe Fittings, Pipe Hangers, Pipe Supports, Flanges and Associated Seals

• MSS SP-43 – Wrought Stainless Steel Butt-Welding Fittings Including Reference to Other Corrosion Resistant Materials
• MSS SP-75 – Specifications for High Test Wrought Buttwelding Fittings
• MSS SP-73 – Brazing Joints for Copper and Copper Alloy Pressure Fittings
• MSS SP-83 – Class 3000 Steel Pipe Unions, Socket-Welding and Threaded
• MSS SP-97 – Integrally Reinforced Forged Branch Outlet Fittings — Socket Welding, Threaded, and Buttwelding Ends
• MSS SP-106 – Cast Copper Alloy Flanges and Flanged Fittings Class 125,150, and 300
• MSS SP-119 – Factory-Made Wrought Belled End Socket Welding Fittings

Difference between “Standard” and “Codes”:

Piping codes imply the requirements of design, fabrication, use of materials, tests and inspection of various pipe and piping system. It has a limited jurisdiction defined by the code. On the other hand, piping standards imply application design and construction rules and requirements for pipe fittings like adapters, flanges, sleeves, elbows, union, tees, valves etc. Like a code, it also has a limited scope defined by the standard.

Factors affecting standards: “Standards” on pipe fittings are based on certain factors like as follows:

• Pressure-temperature ratings
• Size
• Design
• Coatings
• Materials
• Marking
• End connections
• Dimensions and tolerances
• Threading
• Pattern taper etc.

BSP: British Standard Pipe

BSP is the U.K. standard for pipe fittings. This refers to a family of standard screw thread types for interconnecting and sealing pipe ends by mating an external (male) with an internal (female) thread. This has been adopted internationally. It is also known as British Standard Pipe Taper threads (BSPT )or British Standard Pipe Parallel (Straight) threads (BSPP ). While the BSPT achieves pressure tight joints by the threads alone, the BSPP requires a sealing ring.

JIS: Japanese Industrial Standards

This is the Japanese industrial standards or the standards used for industrial activities in Japan for pipe, tube and fittings and published through Japanese Standards Associations.

NPT: National Pipe Thread

National Pipe Thread is a U.S. standard straight (NPS) threads or for tapered (NPT) threads. This is the most popular US standard for pipe fittings. NPT fittings are based on the internal diameter (ID) of the pipe fitting.

BOLTS & NUTS

We are manufacturer of Flange bolts & Nuts and supply high quality

• A193 = This specification covers alloy and stainless steel bolting material for pressure vessels, Valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications.
• A320 = Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service.
• A194 = Standard specification for nuts in many different material types.

AN: Here, “A” stands for Army and “N” stands for Navy

The AN standard was originally designed for the U.S. Military. Whenever, a pipe fitting is AN fittings, it means that the fittings are measured on the outside diameter of the fittings, that is, in 1/16 inch increments.

For example, an AN 4 fitting means a fitting with an external diameter of approximately 4/16″ or ¼”. It is to be noted that approximation is important because AN external diameter is not a direct fit with an equivalent NPT thread.

Dash (-) size

Dash size is the standard used to refer to the inside diameter of a hose. This indicates the size by a two digit number which represents the relative ID in sixteenths of an inch. This is also used interchangeably with AN fittings. For example, a Dash “8” fitting means an AN 8 fitting.

ISO: International Organization for Standardization

ISO is the industrial pipe, tube and fittings standards and specifications from the International Organization for Standardization. ISO standards are numbered. They have format as follows:

“ISO[/IEC] [IS] nnnnn[:yyyy] Title” where

• nnnnn: standard number
• yyyy: year published, and
• Title: describes the subject

General standard

Wide variety for all areas of application

Delivery

Inspection

Visual Inspection is conducted on fittings to check any surface imperfections. Both fittings body and weld are checked for any visible surface imperfections such as dents, die marks, porosity, undercuts, etc. Acceptance as per applicable standard.

Packing

For packing of carbon steel flanges with painting,we would use the bubble wrap to protect the painting.For flanges without painting or oiled with long-term shipment,we would suggest client to use the anti-tarnish paper and plastic bag to prevent the rust.