In this article, I will introduce what copper sheet and copper pipe are, which alloys are usually named for each, how the sizes are written, and why a single line that says copper is not an order.
What is the difference between copper sheet and copper pipe?
Copper sheet and copper pipe are different forms. Sheet, plate and strip are flat. Coil is the same flat product wound. Pipe and tube are hollow. A buyer who writes only copper will be asked which form, because the mill route, the alloy, the size and the test are not the same.
The alloy is the second split. C11000, electrolytic tough pitch copper, is the common sheet and busbar copper. It is about 99.90 percent copper plus silver and contains a small amount of oxygen. It is known for electrical and thermal conductivity. Architectural sheet and strip are commonly this alloy and, in the United States, are often ordered to ASTM B370. C12200, phosphorus-deoxidized high-residual-phosphorus copper, is the copper customarily used for water tube. ASTM B88 covers seamless copper water tube and allows C12200 or C12000 unless the buyer names one. The phosphorus removes oxygen so the tube can be brazed without the embrittlement that oxygen-bearing copper can suffer in that joint. Sheet and pipe therefore often leave the mill as different alloys, not as one copper cut two ways.
How each form is ordered
Sheet is ordered by alloy, temper, thickness and width. Architectural copper is also sold by ounce weight per square foot under ASTM B370, which is a thickness language, not a price unit. Tempers run from soft, for intricate forming, to cold rolled and harder tempers that hold a flashing or a panel. Soft sheet forms and does not hold a long straight edge by itself. Harder tempers do the opposite. Copy the temper.
Pipe and tube are ordered by alloy, outside diameter and wall, then by straight length or coil. In the ASTM B88 size system the outside diameter is one-eighth of an inch larger than the nominal size, and Type K, Type L and Type M are three wall series, K the thickest of the three for a given nominal size. ACR tube for refrigeration is designated by the actual outside diameter and is a different size language. Do not mix a nominal water-tube size with an ACR outside diameter. Say which system the drawing uses.
Bar is a third form, for machining, and it should not be added as a note on a sheet or pipe line. Strip is flat coil under a width the standard treats as strip rather than sheet. If the drawing says strip, keep that word.
What separating the two forms protects
Conductivity, brazing and the fitting all depend on calling the product what it is.
The alloy the joint was designed for
C11000 is the electrical and general sheet alloy. C12200 is the deoxidized tube alloy that brazes cleanly. Substituting one for the other because both are called copper changes the joint or the conductivity the drawing counted on.
A size a fitter can use
Sheet thickness does not describe a tube. Outside diameter and wall, or a B88 type and nominal size, do. A quote in the wrong size language cannot be checked against the fitting.
A temper that forms or stays straight
Soft copper forms and coils. Drawn, hard temper stays straight for a plumbing run. Annealed tube in a straight-length specification, or hard sheet in a spinning die, is the mismatch to avoid.
When to specify sheet, and when to specify pipe
Specify sheet, plate or strip for busbar, roofing, flashing, gutters, gaskets, spun parts and other flat work. Specify coil when a continuous line will cut that flat product. Specify pipe or tube for water, gas, heating and heat-exchange duties that need a hollow section. Specify bar when the part is machined from a solid section.
Do not specify C11000 tube for a brazed water line unless the drawing does. Do not specify C12200 busbar when the duty is the conductivity of electrolytic tough pitch copper and the drawing says C11000. The form and the alloy travel together.
Copper sheet versus copper pipe
Sheet is a flat product sold by thickness or by ounce weight, in a temper, usually C11000 when the drawing is electrical or architectural. Pipe is a hollow product sold by diameter and wall, usually a deoxidized copper such as C12200 when the drawing is water tube. Coil exists on both sides of that split: a flat coil is still sheet or strip, and a tube coil is still tube.
The comparison buyers actually need is which operation comes next. A roofing shop compares sheet temper and ounce weight. A plumbing buyer compares tube type, nominal size and straight or annealed coil. A busbar buyer compares C11000 thickness, width and conductivity. One price list that says copper does not cover the three.
FAQ
These answers are the ones that stop a copper enquiry being quoted in the wrong form.
Is all copper the same alloy?
No. C11000 is the common tough-pitch sheet alloy. C12200 is the deoxidized copper customarily used for water tube. The drawing should name the one it needs.
What is Type L?
In ASTM B88, Type K, Type L and Type M are three wall thicknesses at the same nominal size. Type K is the thickest of the three. The type is not a grade of copper.
What does ounce weight mean on sheet?
Under ASTM B370 it is a thickness, expressed as ounces per square foot. It is not the selling weight of the bundle. The order still needs width, length and temper.
Can sheet be used to make pipe?
Only if the shop is forming and welding its own tube and the alloy is suitable for that joint. It is not a substitute for seamless water tube ordered to B88.
What should a certificate show?
The alloy, the standard, the temper and the size. Ask for it on the enquiry if the project requires it. Do not assume a plumbing tube and a busbar sheet are certified to the same document.
What to send with the enquiry
Name the form, the alloy as the drawing prints it, and the standard. For sheet, give thickness or ounce weight, width, length and temper. For pipe, give the size system, outside diameter and wall or the B88 type and nominal size, plus straight length or coil. Add quantity and whether a certificate is required. Those points are confirmed on the enquiry before the lot is cut.