×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Tubular heat exchanger: US way of writing tubing specs

Tubular heat exchanger: US way of writing tubing specs

Tubular heat exchanger: US way of writing tubing specs

(OP)
Hi all,

my questions might be common sense for you all, but for me as a non US, some questions pop up in my head.

My questions are about how people in the US usually writing the specifications for tubing in tubular heat exchangers. I need to write technical specifications for inquiries.

1. How do you write the outside (or do you say outer?) diameter:
a. 1/2", 3/4", 1-1/4", etc. (as fractions) or
b. 0.5", 0.75", 1.25" (as decimals).

2. How do you write the wall thickness?
a. BWG 12, 14, 16, etc (with BWG).
b. 0.109", 0.083", 0.065" (as decimals in Inch)

3. In Europe we use for tube pitch for example 60mm. How do you choose and write tube pitch in the US?
a. 2.362" (just converted)
b. round up to 2-23/64" (59.93mm)
c. round up to the next ??/16 or ?/8, a.e. 2-3/8" (60.33mm)
d. round up to the next ??/??, but the using of decimals is normal too

I appreciate every answer to help me to understand common writing for engineering in the US. Thank you in advance.

Martin

 

RE: Tubular heat exchanger: US way of writing tubing specs

Martin-

1. Most US engineers are capable of converting fractions to decimals and decimals to fractions. Decimals tend to be easier to type. Either your a) or b) will be perfectly acceptable.

2. Both. However, I prefer decimal since in my opinion there is less opportunity for confusion. (I've never quite figured out why a wire gage is used for tube thickness.) Again, any semi-competent fabricator will be easily able to work with decimals.

3. What's a 64th of an inch? Yep, we use them, but in my experience it is less common to use fractions below a sixteenth. In any case, if given some 32nd or 64th I have to grab the calculator to figure out the decimal. I don't have the need to have more than sixteenths memorized. So I'd pick your c) but write it either with fractions or decimals - 2 3/8" and 2.375" are both acceptable.

When are you metric types going to go with metric time? I figure you should be using a tenth of a day as an equivalent for "hours", a hundredth of a day for "minutes" and a thousandth for "seconds". Just to simplify things!

jt

RE: Tubular heat exchanger: US way of writing tubing specs

1. Either way is OK

2. Either way is OK

3. IMO, (a) is probably best. Several decades ago when there were no CNC machines and the tube holes were laid out by hand you might have needed to specify 2 23/64", but no point in doing so now.

Also, engineers in this field in the US routinely make these conversions in our heads. If I saw a drawing showing a U tube with a straight length of 18'-5 7/16" I could convert that to 221.4375" in my head, but then I'd need a calculator to multiply by 25.4 to convert to mm.

-Christine

RE: Tubular heat exchanger: US way of writing tubing specs

(OP)
Thank you jt and Christine for your help!

Martin

RE: Tubular heat exchanger: US way of writing tubing specs

Metric time? Ha Ha, we are just to lazy to jump in the obvious decimal option, we prefer to compensate/adjust the hexadecimal time every four years (for a while longer).
cheers,
gr2vessels

RE: Tubular heat exchanger: US way of writing tubing specs

How do you define a day in metric time without using hours?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources