Why Does Sprinkler Pipe Come in 21-ft Lengths?

5/9/2019

Basic question but I don't know the history - why do we limit pipe to 21-foot lengths? Manufacturing limitation? Transportation? Just curious on the history there.

Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

3 Comments

Derek

5/9/2019 10:16:22 am

Sch. 40 black steel also comes bundled in 25 ft. lengths. Not sure of the history, but as a fitter I've used both 21s and 25s.

TJ Jones III

5/9/2019 10:17:51 am

You can order pipe in 25' lengths. But the reason 21' has become the standard is due to the production of steel pipe. A heated length of steel is pulled through a hole that will shape it in a tube. 21' was a good length to maintain strength of the steel pipe.

Wayne Ammons

5/9/2019 10:18:17 am

I actually had this same curious question last year and here is the response I got from a contact at Wheatland:

Hey Guys,
Lots of theories I have heard over the years but what seemed to be the most consistent and reasonable answer was this.not too exciting of answer for sure

The 21' length became the standard because of the old way pipe was produced. Pipe was produced in the past using the bell and tongue method. This method of pipe making started with a heated ( red hot - close to melting temperature) length of steel strip and then the strip was manually pulled with a pair of tongues through a bell. Hence the bell and tongue method. The bell was used as both the forming roll and the welding roll. The 21 foot length was the length that could be produced and still keep enough heat in the strip to produce a good weld. A longer length would not have produced suitable weld quality over the entire length. Shorter pipe would not have as good a yield.]

Free Signup

Subscribe and learn something new each day:

Community

Thank You to Our Top
April 2020 Contributors!

1. Mike
2. Sean
3. Franck
4. Dan W.
5. Jonathan

6. Jesse
7. Wayne
8. Jonathan J
9. James
10. Thomas

Your Post

SUBMIT A QUESTION

The Toolkit

Sprinkler Designer or Engineer?

Get all of our tools, including the Sprinkler Database, Friction Loss Calculator, Fire Pump Analyzer and more:

FREE 30-DAY TRIAL

GET THE TOOLKIT

Filters

Exam Prep

2019 PE Prep Guide
(Available Now!)

PE Prep Series
(Available Now!)

Current Leaderboard
(Click to enlarge)

PE Problems

Visit July-October for daily Fire Protection PE Exam sample questions.

Solutions are posted the day after posting.

Comment with your solutions, questions or clarifications.

Please note that questions posted are unofficial and in accordance with NCEES rules are intended to be similar to actual exam questions, not actual exam questions themselves.

RSS Feed

Home - About - Blog - Contact - Exam Prep - Store

Copyright © 2020 MeyerFire, LLC
The views, opinions, and information found on this site represent solely the author shown and do not represent the opinions of any other party, nor does the presented material assume responsibility for its use. Fire protection and life safety systems constitute a critical component for public health and safety and you should consult with a licensed professional for proper design and code adherence. Some (not all) outbound links on this website, such as Amazon links, are affiliate-based where we receive a commission for orders placed elsewhere.