Tubing
For tubing see ASTM A 1016, 213, 268, 269, 519, 632, 789; ASTM B 163, 165, 423, 521, 704 or F 1387;
Fewer ASME standards apply. Exmaples include ASME Sec II SA-213 and ASME SB-423.
Really high pressure low density polyethylene flows in really thick tubing.
Pipe
For pipe see ASTM A 105, 106, 182, 312, 333, 53; ASTM F 1155, 1387, etc. More ASME standards exist such as B31.1, B31.2, B31.3, B31.4, B31.8, B36.10M, B36.19M, etc. The last two are significant.
From ASME B36.10M for welded and seamless wrought steel pipe – and from B36.19M for stainless steel pipe:
"The word pipe is used, as distinguished from tube, to apply to tubular products of dimensions commonly used
for pipeline and piping systems. Pipe NPS 12 (DN 300) and smaller have outside diameters numerically larger than their corresponding sizes. In contrast, the outside diameters of tubes are numerically identical to the size number for all sizes."
I don't know how well separated the two are or how accepted is the distinction that I make. My thoughts about this are that:
1) Pipe is typically manufactured to specific thicknesses (schedules). Tubing often is also, but the tubing thicknesses do not coincide wth those of piping.
2) Pipe is normally thicker than tubing. In fact, I am not aware of any pipe being thinner than tubing of the same nominal size, but this may be my ignorance rather than because it is actually the case.
3) I view piping as something that "is used as is". Piping is rarely bent while tubing often is.
4) Joining methods differ. Piping is typically welded, flanged, or screwed. Tubing is often connected with solder or compression fittings.
These are not hard & fast rules. Rather numerous exceptions can be found.
In addition to the explanations above, here is a rather simple rule I learned and carried with me from a fellow ASME B&PV Code, "old timer (relative term)", boiler friend; "piping" conveys fluids with no intentional heat transfer to surroundings, whereas, tubing is used for heat transfer applications.
The ratio of ID/OD may approach 0.5 for tubing. I think that 6-inch OD is about the top limit. I don't know of the industry standards that apply for 50,000 psi tubing rating but following is a list of size selections:
Sorry warpspeed: hollow structural steel (HSS) is structural, and can be round or rectangular. Rectangular HSS is sometimes given the trival name "box tubing", which confuses matters.
Tubing IS used for carrying fluids, amongst numerous other purposes.
Rigid metal tubing is sized by OD and wall thickness, in North America these being even fractions of an inch: common sizes are 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 1, 1.5, 2, 3 and 4", though oddballs such as 1.25" OD can also be found. Pipe is sized by OD and "schedule" per an archaic standard, which switches back to ODs at 14". Tubing is used for instrumentation and small process lines, high pressure hydraulic and pneumatic services etc. as well as in heat exchangers. In these services it is often joined by compression fittings, orbital welding, and by cone/thread fittings at high pressures.
At sizes to 6", rigid stainless steel tubing is also used extensively in food/beverage and bioprocess applications where sanitary/cleaning considerations predominate over pressure/temperature handling capability. In these services it is often joined by orbital welding and TriClamp-type fittings.
Sure, tubing is commonly used for carrying fluids for reasons of convenience.
For example, exhaust tubing used in Automotive exhaust systems.
Soft drawn copper tubing used in household plumbing.
Boiler tubes carry either fire or water.
But you will find all these "tubes" are still measured and sized by their outside diameter.
The definition still stands:
tubes = OD as nominal size reference
pipe = ID as nominal size reference
For further confusion, how about water /oil well lining - this can be either pipe or tube or well casing but it all ends up as casing.
To answer warpspeed - pipe (US std.)is measured by OD and carries a nominal size - the ID varies due to wall thickness depending on the pressure rating of the particular pipe.
for example all 6" steel pipe have the same OD - 6" pipe sch.40 has ID 6.065", sch 80 ID 5.761" and sch 160 ID 5.187"
You will find similar in BS standard pipe sizing as well.
If you have a fuel fired boiler that burns something, then there will be fire. To heat or boil water you need a boiler, or heat exchanger of some type.
Not to be too pedantic, but that referenced article says, "A fire-tube boiler is a type of boiler in which hot gasesfrom the fire pass through one or more tubes within the boiler."
Heat transfer via fluids, like, not fire in the tubes.
Well you ARE being pedantic, because fire tube boilers is what they are called. Tubes used in fire tube boilers are called fire tubes. That is the perfectly correct engineering terminology for the application.
I am extremely surprised that any engineer has never heard of a fire tube boiler.
The original poster asked a genuine question which I attempted to answer. Some people here are being petty and provocative, which is not at all helpful.
Fire tube boilers indeed contain the flame inside the tube. Not all engineers work with boilers. Some of us work with larger boilers where the heat radiation is on the outside of the tubes. Most of us rarely work with 4-inch OD tubing containing 50,000 psi.
Based upon ASME B36.10, a 2-inch OD tube may fit inside NPS 2 pipe at schedule 40 and below; and will not fit inside the pipe at schedule 80 and above. Various standard specifications define the requirements for several types of tubing and several types of piping.
Piping is designed to more conservative rules because it is exposed to the workspace where workers would be injured if the pipe failed. Tubes are normally enclosed in the walls of a heat exchanger or boiler and their failure is a bit less likely to hurt a worker if they failed.
Tubes are normally enclosed in the walls of a heat exchanger or boiler and their failure is a bit less likely to hurt a worker if they failed.
The statement above applies to heat exchangers, boilers, furnaces etc. but not my transmitter impulse tubing, analyzer sample tubing or the high-pressure process tubing described in some previous posts.
