When working with medium to large size plumbing projects, one of the common problems that would arise and master plumbers face when working with water distribution systems is the flange specifications in valves and piping assemblies.
In addition to the fact that some Master Plumbers are still not fully knowledgeable on how to specify flanges, many plumbing contractors do not know as well the variables in purchasing these items. The problem actually arises when the flanges are already purchased, and lo and behold! THE FLANGES DOES NOT FIT!
The purpose of this article is to bring to the forefront what Master Plumbers like the author himself face in his experience in dealing with flange problems as well as share solutions to these problems. The most common problem in flange specification is with regard to different standards for pipe flanges.
What are the most common Flange Standards?
The following table shows a brief about the most commonly known flange standard used in the plumbing industry:
Flange Standard | Description | Remarks |
|---|---|---|
ISO-7005-1:2011 | Steel flanges for industrial and general service piping systems | A well adopted International Standard for pipe flanges. |
ANSI/ASME B16.5: 2020 | Pipe Flanges And Flanged Fittings: NPS 1/2 Through NPS 24, Metric/Inch Standard | A regional standard, with majority of adoption in the US, and well known and adopted on most US influenced countries. |
AWWA C207-18 | Steel Pipe Flanges for Waterworks Service—Sizes 4 in. through 144 in. (100 mm Through 3,600 mm)
| An industry specific standard for municipal or district water distribution system in the US. |
BS EN 1092-1:2018 | Flanges and their joints. Circular flanges for pipes, valves, fittings and accessories, PN designated Steel flanges | A well adopted European Flange standard. |
Out of these four commonly known standard, the ISO-7005-1 and ANSI/ASME B16.5 is the most known internationally and in the Philippines. This is why the discussions below focuses on these 2 standards.
What standard to use: ANSI or ISO Standard?
One of the most common problems is the standard use in the flange specification, which is whether to use ANSI or ISO standard. It is best to discuss first the origin of these standards and how the market in the Philippines evolved in adoption of the same.
ANSI Standard
ANSI Flange Standard was developed by the American Society of Mechanical Engineers (ASME) and was later adopted by the American National Standards Institute (ANSI). It is widely used all over the world, perhaps mostly because of the American influence after World War II in which most countries with American presence such as the Philippines adopted the American standard. In fact, Master Plumber John F. Hass became the first Chief of the Division of Plumbing Construction and Inspection in the Philippines.
When you talk to veteran plumbers or even carpenters, they still prefer to use inches and feet in measurements. This simply means that the American influence plays an important role in the wide adoption of master plumbers to US standards.
ISO Standard
ISO or International Organization for Standardization which was started primarily by prime European countries was established in 1947 and aims to have a unified goal of ensuring products and services are safe, reliable, and of good quality. Today, ISO have become the prime reference standard for most countries for which the Philippines have been an active member.
The Department of Trade and Industry with its arm Bureau of Philippine Standards (DTI-BPS) is our representative body to the ISO. The BPS develops and publishes Philippine National Standards (PNS). One example of standard related to plumbing is PNS 26:2003 Steel black and hot-dipped zinc-coated (galvanized) longitudinally-welded (for ordinary use) in water, steam, gas, and air lines. To enforce this standard, the DTI-BPS issues Memorandum Circulars for compliance by the suppliers, distributors, and manufacturers of these products.
Which standard to use?
Given the adoption of ISO standards by DTI-BPS and the latest developments in supply of products is the Asia-Pacific Region, it is advisable to already adopt ISO standards in our professional practice such as in material specifications.
One example that I have faced in the practice is in ordering of ductile iron valves. Though ANSI flanged-valves are still available in the market, I have found out that the cost for this valves are much higher and the lead time is much longer. This is because the major market for ANSI flanged valves are in the US, therefore, stocking of these valves are going to the other side of the globe. Most Asia-Pacific countries already adopted ISO standard, and we would expect ISO standards to be adhered to by most if not all countries in the future. The map below shows how ISO is adopted throughout the world, even in the US.
Photo source: ISO website
ISO 7005-1
The ISO standard used in the specifications and dimensional requirements of steel flanges is ISO 7005-1 with its 2011 latest edition. This standard shows the specifications of flanges in accordance to its design, strength, dimensions, among others. This is used not only to flanges but also to valves and piping accessories which uses flange connections. The following photo shows some of the contents of ISO 7005-1: 1992 Edition.
Figure above shows sample ISO Flange Standard (Source: ISO:7005-1: 1992)
Figure above shows sample ISO Flange dimensional reference (Source: ISO:7005-1: 1992)
Take-aways in Flange specification and installation:
The author have had some lessons learned from experience in the specification and installation of flanged valves and connections. It is his intent to share these to help master plumbers avoid these pitfalls:
1. Do not use plastic pipe flanges. Nowadays, the most common pipe and fittings used in building water distribution systems are plastics such as PPR and HDPE. Most if not all threaded connections are up to 63mm (2”) diameter only. With this, pipes above 2” requires flanged valves and accessories.
Some PPR manufacturers produce PPR flanges. The problem with this is you cannot overtighten enough the PPR or HDPE flanges or else it will deform. This has caused leaks in my project and I eventually have them replaced with steel ring flanges. Use steel ring flanges coupled with a PPR or HDPE flange adaptor or also commonly known as Stub-End such as shown in the image below.
2. Use Flanged Short Pipe to connect two flanged valves together. If you are connecting two flanged valves together, it is noteworthy not to connect them directly together. This is because some valves such as gate valves, diaphragm-type valves, check valves, and y-strainer have bulky portions where the flanged bolt could just be inserted one way only. If these bulky portions match together, you cannot insert the flange bolt in either direction. Instead, use a Flanges Short Pipe which is either fabricated or purchased such as the one below from AVK.
Image shows common problem in the insertion of flange bolts.
Photo shows an example of a manufactured Flanged Short Pipe from AVK.
Photo Source: Screen shot from Bermad Video (YouTube) – This sample photo shows the use of Flanged Short Pipe between two valves. Without the short pipe, there is no way to insert the flange bolt.
3. Specify flanges completely and correctly. Whenever you specify valves on piping assemblies requiring flanged connections, specify them correctly and completely to avoid wrong purchase and delays in installation. The following is the recommended way to specify flanged valves and accessories:
If you have additional inputs from your own experience, feel free to comment below for forum discussions!
Author:
Ar. James Ray L. Magdadaro, PIA, UAP, NAMPAP, ASPE
Registered Master Plumber (PRC Reg. 6491)
Managing Partner - MEP GLOBAL CO.
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