Equivalent Length Calculations For Pipe Fittings And Valves

November 16, 2011 is kind of a momentous day in my life. 25 years ago on this very day a young girl joined hands with me and both of us pledged our love and devotion to each other till death do us apart. This woman has stood by me through all the ups and downs in this long journey of 25 years. She has primarily been responsible for our children growing up as responsible citizens of this society. Today's blog entry is dedicated to my wife Anu and for our silver jubilee anniversary.

Enough of the sentimental stuff. Let's get down to the topic in hand. Equivalent length of pipe fittings and valves has been a topic often debated on engineeering forums and there is a lot of information available freely availbale on the internet related to the subject. In fact our own forum has a very wonderful article devoted to the subject at the following link:

http://www.cheresour.../eqlength.shtml

Crane Technical Paper No: 410, "Flow of Fluids through Valves, Fittings and Pipe" has been the primary source for determining the equivalent length for pipe fittings and valves over the years specifically when you are dealing with turbulent flow and utilizing the Moody Friction factor chart. Crane Paper 410 can be considered a kind of pioneering work in the field of fluid flow and I would recommend all chemical engineers to go throught this "treatise" on fluid flow. The concept of the resistance coefficient 'K' for valves and ffitings was in fact introduced through this paper. One of the limitations of the Crane method for determining the equivalent length was the equivalent lengths for pipe fittings and valves in laminar flow regime. The Hooper 2-K method and the Darby 3-K method could address the calculation of the equivalent lengths in the laminar flow regime by essentially co-relating equivalent lengths as a function of the Reynolds number for a given pipe diameter. For a great discussion on the 2-K method readers can refer the following link:

http://www.cheresour...1882#entry31882

Despite all the hoopla-hoo about the new 2-K and 3-K methods for providing more accurate equivalent length calculations the Crane method for determining the equivalent length still remains universally accepted. Many standard chemical engineering books have utilized the principles of the Crane paper to develop charts for the resistance coefficient 'K' for various fittings and valves which when multiplied with the pipe diameter gives the equivalent length for the particualr pipe fitting or valve. One of the most popular books in the oil and gas field "GPSA Engineering Databook", 11th edition, SI units provides a chart (Fig 17-4) in Section 17, "Fluid Flow & Piping" for the equivalent lengths of the commonly used fittings and valves as a function of the resistance coefficient and the nominal pipe diameter. It however misses out on pipe reduction and pipe exapnsion through concentric reducers / expanders and sudden contraction / expansion.

The main intention of today's blog entry was to provide an excel spreadsheet for equivalent length calculations for pipe fittings and valves using the combination of the GPSA Engineering Databook and the Crane Technical Paper No: 410. The contraction / expansion of pipe has been considered from the Crane Paper 410, since it provides a very comprehensive discussion on how to determine equivalent length for pipe contraction and expansion. For concentric reducers / expanders the actual dimensions are considered for various standard reducers based on ASME B16.9 - "Factory-Made Wrought Buttweld Fittings".

The excel workbook is attached with this blog entry. Hope all of you will enjoy reading this blog entry and find the excel workbook useful. Looking forward to comments from the readers and members of "Cheresources".

MS Excel file available in the Download section at:
http://www.cheresour...pes-and-valves/

Regards,
Ankur.