What’s the Difference Between ASME B16.47 Series A and Series B Flanges?


ASME B16.47 Large Diameter Steel Flange Standard

In November of 1980, Subcommittee C of the American Society of Mechanical Engineers (ASME) B16 began work on the B16.47 Large Diameter Steel Flange Standard to standardize dimensions, tolerances, markings, and materials for Nominal Pipe Sizes 26” to 60”. Prior to this in July of 1952, MSS-SP44 covered 12” thru 60” Nominal Pipe Sizes (NPS), in 150# to 900# pressure ratings in raised face (RF), flat faced (FF),and ring type joint (RTJ) facing. The initial draft was developed in December of 1982, and went thru several adjustments before being approved and published in 1990 as Series A (Duplicating MSS-SP44 specification) and Series B (Replacing API-605 specification). Both the Series A and Series B are a weld neck and blind specifications only. Series A and Series B are manufactured in Carbon, Stainless and other alloy materials.


What’s the difference between ASME B16.47 Series A vs Series B?

Physical attributes for Series A flanges are typically thicker in flange thickness, heavier in weight, and have large diameter bolt holes in comparison to Series B in the same size and pressure rating. Series B flanges generally have more bolt holes than are in smaller in diameter, generating the need for smaller bolting hardware.  It is important to note Series A and Series B flanges are non-compatible in bolting between each other.

Application of Series A flanges are normally used for industrial connectors such as valves, pumps and pipeline separations. Series B flanges are commonly used in pipeline application.

Price points for Series A flanges tend to be more expensive due to increased steel weight, whereas Series B consumes less steel weight therefore reducing cost.

In Conclusion: ASME B 16.47 Series A and Series B flanges are for large diameter applications for piping projects from 26” thru 60”. Both Series can be manufactured using carbon, stainless, and other alloy materials.  Series A is a carryover from MSS SP44 and Series B from API 605, thus creating a more uniform standardization for the industry thru ASME B16.47.

Please contact Coastal Flange with any questions or to receive a bid winning quote tailored to your needs.

Phone:  713-937-3333
Email: Sales@coastalflange.com

Flange Facing for B16.5 and B16.47 Flanges

Flange Facing for B16.5 &  B16.47 Flanges

The flange face is the surface area where the gasket seats to seal the flanged connection. During fabrication the flange is always fitted perpendicular to the pipe to prevent any leakage of the connecting joint. The most common types of flange faces are the Raised Face or RF, the Flat Faced or FF, and the Ring Type Joint or RTJ.

The Raised Face

1/16″ Raised Face Finish
1/4″ Raised Face Finish on High Pressure Flange

The Raised Face is the most common for the ANSI B16.5 and ASME B16.47 Flanges. The main scope of the Raised Face design is to concentrate the pressure of the two mating Flanges on a small surface area to increase the strength of the seal. The Raised Face is machined inside the bolt circle and is 1/16” in height for the 150# and 300# classes and ¼” for the 400# and above classes. For the 150# and 300# classes this dimension is included in the overall length of the Flange. For the 400# and above class Flanges the ¼” must be added to the overall length of the Flange.

Phonographic Finish

Serrated Concentric Finish
Serrated Spiral Finish on Flange in processing

The Standard Facing for the B16.5 and B16.47 Flanges is known as a Phonographic Finish which is a continuous groove which is generated by using a 1/16” Radius round nose tool with a cutting speed of 1/32” per revolution, this results in a 125-250 RMS finish. The customer may specify a different finish for special applications.

The Flat Face

Flat Faced Lightweight Hub Flanges in Production phase

The contact surface for Flat Faced Flanges will have the same height across the face of the Flange. Per ASME B31.3 a Raised Face Flange should never be bolted to a Flat Faced Flange as this could result in a leak at the Flanged joint.

The Ring Type Joint

Ring Type Joint Flange manufactured at Coastal Flange.

The Ring Type Joint Flange has a circular groove machined in the Face and is used for high pressure and high temperature applications. The RTJ as well as the other facings will be covered at a later time.

Please contact Coastal Flange with any questions or to receive a bid winning quote tailored to your needs.

Phone:  713-937-3333
Email: Sales@coastalflange.com


Other related posts:

Raised Face vs. Flat Face Flanges

What are the 5 Basic Flange Face Finishes?


History of AWWA Ring and Hub Flanges

The American Water Works Association

The American Water Works Association was founded on March 29, 1881 in St. Louis, Missouri by 22 men representing water utilities in Illinois, Indiana, Iowa, Kansas, Kentucky, and Tennessee.

The founding members adopted a constitution with the goal of the association being “for the exchange of information pertaining to the management of water-works, for the mutual advancement of consumers and water companies, and for the purpose of securing economy and uniformity in the operations of water-works.”

The AWWA Today

Today, there are more than 180 AWWA Standards that cover everything from the well to storage tanks, water treatment plants, to distribution systems. AWWA standards describe the minimum requirements and do not contain all of the engineering and administrative information contained in specifications. C207 and C228 cover the pipe flanges in carbon steel and stainless steel.

In 2008 the AWWA introduced C228 for stainless steel flanges for use with stainless steel pipe in water works service. This standard is for ring type slip on and blind flanges. Pressure ratings for water service are SA–50 psi., SB-86 psi., SD-150 psi., and SE-275 psi. In 2013 C207 dropped the hub flanges from the standard making it ring type slip on and blind flange only.

As urban development and the impact of industrialization and technology changes, the AWWA will continue to lead the industry with its standards and creation of best practices.

Sources: AWWA History

Raised Face Flange vs. Flat Faced Flange

Raised Face Flange vs. Flat Faced Flange

The key identifier between the raised face and flat face flange is that the raised face is raised above the bolting circle face.  The raised face and flat face flanges are both industry standard in the pipe fitting and flange industry.  This post will showcase details on the differences and uses of the raised face and flat face flanges.

Raised Face Flanges

Raised Face Finish on Flange manufactured at Coastal Flange

The raised face (RF) is the most common type of flange facing used. It is called a raised face flange because it has a raised surface above the bolting circle where the gasket is placed.  These flanges are widely used in oil and gas pipelines. They are appropriate for both high and low temperatures and pressures.

The main purpose of the RF flange is to concentrate the contact pressure on the gasket area, resulting in increased strength of the seal. Diameter and height are in ASME 16.5 defined by pressure class and diameter. The higher the pressure rating, the larger the diameter of the flange, the number of bolts and thickness of the flange itself, and the raise face are.  The Standard Flange Facing for ASME B16.5 and ASME B16.47 is a 125-250 RMS Finish.

 Flat Face Flanges

Large Diameter Custom Ring with Flat Face Finish

Flat face (FF) flanges are similar to raised face flanges, but they have a flat surface.  These flanges have a gasket surface in the same plane as the bolting circle face.   The flat face is the simplest type of flange face available.

The intention of a flat face flange is to prevent the bending movement that is put on flanges as the bolts are torqued. Usage of flat face flanges are those in which the mating flange or flanged fitting is casted. FF flanges can be seen in low-pressure and low temperature situations like in water treatment facilities. The finish for the ASME B16.47 flat face flanges is the same as the raised face with a finish of 125-250 RMS.

How to Choose the Right Flange for your Project

When it comes to the best flange face for your project there are many factors such as pressure, temperature and purpose. Flat face flanges are best for operations with low pressure and low temperature.  Raise face flanges are designed to endure more challenging situations. To learn more about how to order a custom flange with us, click here!

Our expert sales team and engineers at Coastal Flange are available to assist you with your next project.  We can help you find the right flange and face for your needs.

Contact Coastal Flange with any questions or to receive a quote tailored.
Phone:  713-937-3333
Email: Sales@coastalflange.com

What is a Ring Type Joint (RTJ) Flange?

 Ring Type Joint Flanges

Ring Type Joint Flange from different viewpoints.

The Ring Type Joint or RTJ refers to the type of Gasket required for the Flange. The Ring Type Joint was designed for the Petroleum and Petrochemical industries where higher pressures and temperatures are present. The sealing surface is a high tolerance groove cut into the face of the Flange with a maximum of a 63 RMS finish. The seal is achieved when the bolts are torqued down compressing the RTJ ring into the groove of the Flanges.

Ring Type Joint Flange manufactured at Coastal Flange.
RTJ Flange painted and manufactured by Coastal Flange

Ring Type Joint gaskets are manufactured to ASME  B16.20 Standards and are suited for use with the Flanges made to ANSI B16.5, ASME B16.47 Series A and API 6A Standards.

Benefits of using an RTJ flange and ring is that the gasket is restricted to a groove that has two sealing surfaces. The groove ensures the ring centers itself when the bolts are tightened.  The sealing pressure increases when the process pressure increases on these type of flanges.

A disadvantage of using RTJ flanges is that the grooves can collect dirt or moisture when the flange is open.  It is important that the grooves and ring gaskets are properly aligned in order to create the proper seal.  The seal must be maintained throughout the operating cycle

Technical data sheets on Ring Joint Flanges are published on the Coastal Flange website for your convenience.

RTJ Gasket Types

RTJ Gaskets

There are three Types of Ring Type Joint gasket designs, the R Type, RX Type and BX Type. The R Type is the most often used supplied with two different profiles, oval or octagonal. The oval type was the original design with an oval shaped groove machined into the Flange Face. The octagonal RTJ is a modification to the oval design and is the most common because of its sealing efficiency. The R and RX octagonal gaskets use the same groove design. The RX is designed for higher pressure up to 5000 psi and is more effective where vibration and shock loading is present. The BX Type gasket is only to be used in API 6BX Type Flanges and is good for pressure ratings up to 20,000 psi. The RTJ Flange will include the Ring Number in the stamping on the Out Side Diameter of the Flange to identify the Type of Ring to be used.

Contact Coastal Flange with any questions or to receive a quote tailored.
Phone:  713-937-3333
Email: Sales@coastalflange.com

How to Order Custom Flanges

How to Order Custom Flanges

Coastal Flange mainly focuses on industry specific flanges such as AWWA, ANSI, ASME and industry standard flanges we also specialize in custom order flanges.  With a wide range of industries, shops, and systems dependent upon high performance flanges, custom pipe flanges are essential to getting a job done right. Modified and custom flanges for specialty projects can offer the same quality, inspection requirements, and performance expectations of industry standard components, but offer a particular size, material, or fit for a unique application.

We work with industry leaders and experts across the USA, Canada, Mexico, Latin and South America on a daily basis to provide custom flanges.  We also work with clients from Europe, Asia, Africa, and the Middle East. 

At Coastal Flange we work with customer specifications and project requirements to tailor a product that will ensure success!


How does Custom Flange Ordering Work?

Job shops specializing in custom work often stock large quantities of raw material ready to be crafted into the shape, size, and style of flange a customer requires. This includes modifications on industry standard flanges or unique shapes such as:

  • Square Pipe Flanges
  • Square OD x Circle ID Flanges
  • Flanges with dual bolt patterns
  • Flanges with spools between custom layers
  • Reduced Flanges (Reduced Weld necks and Reduced Slip-ons)

Using design tools such as AutoCAD, flange specialists can develop prints and designs for clear, precise fabrication, no matter how specialized a project may be.


How to Order a Custom Flange

The first step to ordering a custom flange is to gather as much information as possible about the flange you will need. Include details such as:

  1. Project Requirements: Pressure class, facing, connection type, pipe size, specifications 
  2. Material Grade 
  3. How many flanges you need

Common Flange Standards and Specifications

Special flanges and fittings and custom forgings can be designed to meet any number of unique specifications and standards. Some common classifications for custom pipe flanges include:

  • AWWA, the American Water Works Association
  • ASME, the American Society of Mechanical Engineers
  • ANSI, the American National Standards Institute
  • CL 125 Lightweight
  • Tube Turns
  • Large Industry Standard
  • Metric System Flanges


Custom Flange Types

Regardless of custom sizing or specifications, the fundamental design of most flanges falls under six common styles created to close, connect, cover, or support pipes and pipe systems.


These flange types include:

  • Slip-on Flanges – available in both standard and reduced sizes and both ring and hub style, manufactured to dimensions that will slide over a pipe with a snug fit
  • Weld Neck Flanges – available in standard and reduced sizes, manufactured to the inside diameter dimensions of a pipe for attachment via welding
  • Blind Flanges – available to seal both pipes and vessels
  • Lap Joint Flanges – available in a range of sizes to pair with stub end fittings for easy dismantling
  • Threaded Flanges – engineered to fit pipes with external threads for weld-free fits
  • Socket-weld Flanges – designed with a socket fit and top weld for ideal inner flow in pipe systems


Material Grades and Performance

Custom pipe flanges can be manufactured from a wide variety of materials and material grades. Carbon steel is a popular solution, as are stainless steel and specialty alloys, depending upon the industry. Plate and forged are also common, as are titanium and aluminum for lightweight jobs.

Q & A about Coastal Custom Orders:


Can Coastal Flange provide assistance with drawings for custom flanges? 

Yes. Our ability to manufacture custom flanges does not always depend on an approved print. However, Coastal Flange has personnel experienced in AutoCad and we are able to quickly produce prints of custom flanges. Prints for custom flanges can be used to clarify information or provide an opportunity for the customer to sign a shop print and approve work to begin. With Autocad and our expert staff, custom flanges that conform to the most stringent designs are not a problem.


What about Square Pipe Flanges? Is Coastal Flange capable of manufacturing square custom flanges?

Yes. Coastal Flange has experience manufacturing square pipe flanges with tie rod holes as well as square OD x circle ID flanges for custom applications. Other custom flanges that are commonly made at Coastal Flange include custom flanges with dual bolt patterns and custom flanges with spools between the custom flanges. Coastal Flange also makes custom flanges that are a variation of reducing flanges, including reducing weld necks and reducing slip-ons.



What are Metal Flange Forgings?

Forging is the process of forming and shaping Metal using a Hammering, Pressing or Rolling method. There are four main types of processes used to produce Forgings. These are Seamless Rolled Ring, Open Die, Closed Die and Cold Pressed. The Flange Industry uses two Types. The Seamless Rolled Ring and Closed Die processes. All are started by cutting the appropriate sized billet of the required material grade, heating in an oven to the needed temperature, then working the material to the desired shape. After Forging the material is subjected to Heat Treatment specific to the Material Grade.

Seamless Rolled Ring Forging for 32″ 150# Weld Neck in SA-105 Normalized material

The Seamless Rolled Ring Forgings are made similar to other die Forgings. The Ring Forgings are formed by opposing rotating circular dies that simultaneously compresses the heated billet into a ring shape. Rolled Ring Forgings are available in excess of 200” in diameter.

Hammer Forge used in Open Die Forging Process
Open Die 18″ Diameter Forged Bar

Open Die Forgings are produced by using two flat or shaped opposing Dies that are either Hydraulically compressed or Hammered to form the desired shape. The base material is open on the sides to allow for lateral movement, making for larger and heavier Forgings. These are typically Blocks, Bars or Cylinders.

Closed Die Forgings for 10″ 150# Slip On Flanges in SA-105 Normalized material

The Closed Die Forgings are sometimes called Impression Die Forgings and are made using the same process as the Open Die Forgings. With this process the heated raw material is placed in a closed Die where no material is left exposed. The Die is then compressed either using the Hydraulic or Hammer method. This process requires much greater compression to ensure the cavities of the die are completely filled to form the part. Closed Die parts are smaller and produce near perfect shapes allowing for minimal machine work and high production runs.

Cold Forged Hex Nut
Cold Forged Gear
Cold Forged Bicycle Part

Cold Pressed Forging is the most common of the Forging processes. Cold forgings are produced at room temperatures and require no preheating of raw material.  Cold Forging produces parts that are free of scale and formed to tight tolerances so that machining is not required. Post production annealing is sometimes required depending on the material being formed and the application. Cold Formed parts are light weight and used in all types of manufacturing.

Contact Coastal Flange with any questions or to receive a quote tailored.
Phone:  713-937-3333
Email: Sales@coastalflange.com

What are Lap Joint Flanges?

A Stub end Flange or more commonly called Lap Joint Flanges are used with Stub Ends. A Stub End adapter slides thru the Flange and is welded to the pipe. The Lap Joint Flange is similar to theSlip On Flange except it is flat across the face and has a radius machined at the bore. This allows it to rotate freely around the Stub for easy alignment to the mating Flange.

When when bolted up the Lap Joint flange compresses the Stub end to the gasket and the other mating surface and makes the seal. Stub Ends and Lap Joints are normally used in Alloy piping systems. These flanges are usually made from less expensive Carbon Steel materials since they are not exposed to the process fluids. Lap Joint Flanges are supplied in all Diameters and pressure classes. Coastal Flange can provide pipe flanges in all material grades, specifications, and sizes.

24″ 300# Lap Joint Flanges for Type B Stub Ends ready for inspection.
36″ 300# Lap Joint Flanges for Type B Stub Ends going to the Drills.

Type A Stub Ends are standard length and Type B Stub Ends are longer in Length for the Higher Pressure Flanges with Longer overall length.

48″ 300# Lap Joint Flanges for Type C Stub Ends

Type C Stub Ends are made on application from Pipe and then the Gasket Surface is machined to fit the project requirement.

Call Coastal Flange with any questions or to receive a quote for any of your pipe  flange needs.
Phone:  713-937-3333
Email: Sales@coastalflange.com

What is a Skirt Flange?

16″ AWWA Class E Skirt Flange being welded in the positioner.
18″ AWWA Class E Skirt Flanges after refacing going to be drilled.
Custom Engineered AWWA Class E Skirt Flanges being readied for shipment.

Skirt Flanges are just one of the Custom Engineered Pipe Flanges we produce here at Coastal Flange. A Skirt Flange is a Pipe Flange with a short piece of Pipe welded to it for use with cement lined pipe. The Skirt Flange is lined with a Cement-Mortar mix and is applied according to AWWA C 205 guidelines.

Skirt Flanges are commonly used at treatment plants and pumping stations where Flanged connections are made.  Cement lined pipe was first used in 1922 in Charleston Couth Carolina by the Charleston Commission of Public works for underground potable water supply lines. The Municipal Water Districts have used the Cement Lined Piping Systems for several reasons since then. The primary reason is the lining prevents tuberculation and keeps the water pure, it also stops discoloration and odors. When used for underground piping systems the risk of leaks is eliminated, reducing maintenance and replacement cost from pipe failure.

Contact Coastal Flange with any questions or to receive a quote tailored.
Phone:  713-937-3333
Email: Sales@coastalflange.com

What are the Types of Flange Gaskets?

In Piping Systems a Flange Gasket is placed between two connecting Flanges to create a leak proof seal. The three primary types of Flange Gaskets are Non-metallic, Semi metallic and Metal Gaskets.

Photo Provided by Project Materials

The Non-metallic Flange Gaskets are used in low pressure, low temperature and noncritical service applications. These are supplied as a Ring Gasket for Raised Face Flanges and a Full Face Flange Gasket for Utility or Water Works Service in 150# and 300# ratings. These Flange Gaskets are made from a soft material to seat in the Grooves of the Flange Face.

The Semi Metallic Flange Gasket or Composite Flange Gaskets are a combination of metal and nonmetal materials based on Product and Service requirements. The most widely used is the Spiral wound Flange Gasket, it is suitable for a wide range of temperature and pressure Classes. Normally a filler of Graphite or PTFE combined with a Stainless Steel or other Alloy is formed into a Spiral winding with a metal outer ring to seal the Flanged joint when compressed.

The Metal Flange Gasket or Ring Type Joint Flange Gasket is all metal Flange Gasket made from Carbon Steel, Stainless Steel or other Exotic Alloy and is commonly called a RTJ Gasket. The RTJ Flange Gaskets are designed to be used in high pressure, high temperature critical applications. The RTJ Flange Gasket fits into either an oval or rectangular cut groove cut into the face of the mating Flanges. When tightened these Flange Gaskets are squeezed into the grooves and will provide a strong and long lasting seal at the Flanged connection.

Contact Coastal Flange with any questions or to receive a quote tailored.
Phone:  713-937-3333
Email: Sales@coastalflange.com