What is ASTM B88?
ASTM B88 is the standard specification for seamless Copper Water Tube, drawn from C12200 (Cu-DHP, phosphorus-deoxidized) and supplied in three wall-thickness classes - Type K, Type L, and Type M - for water distribution, sanitary, heating, and fire-protection service. The "B88" mark on a tube's spec sheet is the engineering signal that the tube satisfies the dimensional, mechanical, and testing requirements of the standard.
The full US-customary standard covers nominal sizes from 1/4" to 12"; the metric counterpart is ASTM B88M. All three types are made from C12200 - ASTM B88 calls for a deoxidized grade because the brazed and soldered joints common in water-tube installation are incompatible with the residual oxygen that C11000 (ETP) carries.
Export Case : Canada – ASTM B88 Large Diameter Custom Copper Tube
We recently completed an export order of C12200 copper tube to Canada. The product was strictly manufactured according to ASTM B88 standard and is a large diameter, non-standard custom tube, used in the main water supply system of a local commercial building.
ASTM B88 Wall Thickness Reference - Type K vs Type L vs Type M
The table below lists the nominal wall thickness for each type at the most commonly stocked sizes. Specifiers name the type, not the wall thickness directly - the type is the wall-thickness category in the standard.
| Nominal size | Type K (thickest) | Type L (medium) | Type M (thinnest) |
|---|---|---|---|
| 1/4" (6 mm) | 0.035" (0.89 mm) | 0.030" (0.76 mm) | 0.025" (0.64 mm) |
| 3/8" (10 mm) | 0.049" (1.24 mm) | 0.035" (0.89 mm) | 0.025" (0.64 mm) |
| 1/2" (15 mm) | 0.049" (1.24 mm) | 0.040" (1.02 mm) | 0.028" (0.71 mm) |
| 5/8" (18 mm) | 0.049" (1.24 mm) | 0.040" (1.02 mm) | 0.030" (0.76 mm) |
| 3/4" (22 mm) | 0.065" (1.65 mm) | 0.045" (1.14 mm) | 0.032" (0.81 mm) |
| 1" (28 mm) | 0.065" (1.65 mm) | 0.050" (1.27 mm) | 0.035" (0.89 mm) |
| 1-1/4" (35 mm) | 0.065" (1.65 mm) | 0.055" (1.40 mm) | 0.042" (1.07 mm) |
| 1-1/2" (42 mm) | 0.072" (1.83 mm) | 0.060" (1.52 mm) | 0.049" (1.24 mm) |
| 2" (54 mm) | 0.083" (2.11 mm) | 0.070" (1.78 mm) | 0.058" (1.47 mm) |
| 3" (80 mm) | 0.109" (2.77 mm) | 0.090" (2.29 mm) | 0.072" (1.83 mm) |
| 4" (108 mm) | 0.134" (3.40 mm) | 0.110" (2.79 mm) | 0.095" (2.41 mm) |
| 6" (159 mm) | 0.192" (4.88 mm) | 0.140" (3.56 mm) | 0.122" (3.10 mm) |
Need ASTM B88 Type K/L/ M copper tube for an order? Send your size list
Type K, Type L, Type M - When to Choose Each
Type K - thickest wall, highest-pressure service
Specify Type K when the line is buried, exposed to high pressure, or required by code to be the heaviest class. Typical uses:
Underground water service from street to building.
Fire-sprinkler mains in NFPA 13 / NFPA 24 systems.
Industrial process water, compressed-air, and vacuum lines.
Hospital and medical-gas mains under ASTM B819 cross-reference.
Type L - medium wall, the default indoor choice
Type L is the workhorse of residential and commercial plumbing. Most project teams default to Type L unless the spec calls for K or M. Typical uses:
Indoor potable-water distribution (hot and cold lines).
Hydronic heating and chilled-water risers.
Solar water-heater piping and heat-exchanger headers.
Fire-sprinkler risers (NFPA 13 / NFPA 13R, in many jurisdictions).
Type M - thinnest wall, light-duty residential
Specify Type M only when local code permits the thinnest class and the line is above-ground residential. Typical uses:
Above-ground residential water distribution (in jurisdictions that permit M).
Low-pressure hydronic loops under domestic rating.
HVAC condensate lines (informal, not B88-listed).
Engineering Decision Matrix - Type K / L / M
| Application | Typical Type | Why |
|---|---|---|
| Underground water service entrance | Type K | Mechanical protection, code requirement |
| Fire-sprinkler main (NFPA 13 / 24) | Type K | Heaviest wall, code-required |
| Hospital / medical-gas main | Type K (with B819 callout) | Deoxidized tube under code-mandated thickness |
| Indoor commercial water distribution | Type L | Cost-effective, code-accepted, brazable |
| Hydronic heating / chilled water | Type L | Standard practice, good fatigue resistance |
| Solar water heater piping | Type L | Handles thermal cycling; brazed joint compatible |
| Fire-sprinkler riser (NFPA 13 / 13R) | Type L | Accepted by most sprinkler codes |
| Above-ground residential water (where code permits) | Type M | Lowest cost for low-pressure service |
| Hydronic low-pressure loop, residential | Type M | Where local code allows the thinnest class |
How Our Mill Supplies ASTM B88 Tube
The same mill that supplies drawn Copper Tube to ASTM B88, B280, and B819 also produces the matching Copper fittings - including elbows, tees, couplings, reducers, and adapters - in the same C12200 base, so a brazed system is mono-alloy end-to-end.
Form, length, and temper
Straight tube: 3 m or 6 m lengths, all three types and all stocked sizes.
Coil tube: 15 m / 30 m coils for soft-temper (O60) sizes up to 22 mm OD - common in residential and solar loops.
U-bend tube: for refrigerant and heat-exchanger headers.
Temper: O60 (annealed), H55 (light-drawn), H80 (drawn / hard).
Certifications, packaging, and lead time
EN 10204 Type 3.1 MTC for every heat.
Third-party inspection by SGS, BV, TÜV, or any client-nominated body welcomed.
Mill tests: hydrostatic, eddy-current, expansion / flare, hardness, chemical analysis.
Packaging: end-capped, plastic-sleeved bundles in woven-belt or plywood-crate formats.
Lead time: 15–25 working days for stocked size ranges; 25–40 days for special-temper orders.
MOQ: 1 metric ton per size; price breaks on volume.
Pricing and export
Standard quotation is FOB China from Tianjin, Qingdao, Shanghai, Ningbo, or Shenzhen; CIF and CFR to any world port - including Caribbean, Latin American, Middle Eastern, and African destinations - quoted on request. Payment: T/T (30 % deposit + 70 % against B/L copy), L/C at sight, D/P. Transit to Caribbean and Latin-American ports is typically 28–40 days port-to-port via Panama Canal. A 20'GP FCL (≈ 18–22 t) is the recommended shipping method for trunk-size orders; LCL is reserved for samples and mixed-size pre-production trials.
FAQ
Q: 1. Is ASTM B88 the same as EN 1057?
A: Both standards cover seamless copper tube for water, but they belong to different systems. ASTM B88 uses three Type classes (K / L / M) in US-customary dimensions; EN 1057 uses thickness grades R (thick) / S / T in metric dimensions. The same C12200 base material is used. Cross-reference between the two is straightforward - confirm dimensions by size chart before substituting.
Q: 2. Can Type L be used for fire sprinklers?
A: In many US jurisdictions, Type L is permitted for fire-sprinkler risers (NFPA 13 / 13R). Horizontal sprinkler mains (mains feeding the branch lines) typically require Type K per NFPA 24. Confirm with the local Authority Having Jurisdiction (AHJ) before specifying.
Q: 3. Which type is the cheapest?
A: Type M uses the least copper per metre and is the lowest-cost class - typically 15–25 % cheaper than Type L of the same nominal size; Type K carries a 30–50 % premium over Type M. Material cost per metre of installed system - including fittings and labour - is often within 5 % across the three classes, so a thin-class saving can be erased by reduced joint confidence on a long run.
Q: 4. Can I get Type K, L, and M in the same shipment?
A: Yes. The mill runs all three types on parallel drawing benches; mixed containers ship segregated by bundle with a single 3.1 MTC per heat number.
Q: 5. What temper is supplied for plumbing?
A: Most distribution yards stock Type L in O60 (annealed / soft) for field bending and brazing, and H80 (drawn / hard) for above-ground runs where straightness is required. Specifiers name temper separately from the Type.
Q: 6. Do you supply straight lengths or coils?
A: Both. Straight lengths in 3 m or 6 m for all sizes; coils (15 m / 30 m) for soft-temper sizes up to 22 mm OD. Custom cut-to-length bundles are available for OEM accounts.
Q: 7. Is a free sample available?
A: Yes. Cut-off samples of each Type K / L / M and a small fitting kit are dispatched by international courier at cost; the courier account number from the purchaser's side speeds the booking.
