Overview
Specifies seamless copper tube for general engineering, heat transfer, and light-industrial applications where dimensional accuracy and material integrity are required. Covers copper alloys including C10200 (oxygen-free copper) and C12200 (phosphorus-deoxidised copper, the most common grade), supplied in annealed (soft) or hard-drawn temper. Tube is sized by outside diameter and wall thickness. B75 is the foundational seamless copper tube standard; plumbing (B88), refrigeration/ACR (B280), and condenser/heat-exchanger tube (B111) each have their own dedicated specifications built on similar principles.
Scope & Applicability
Applies To Industries
Covers — seamless copper tube in the following alloy and temper combinations:
Copper alloys covered:
| UNS | Common Name | Cu Content | Key Characteristic |
|---|---|---|---|
| C10200 | Oxygen-Free (OF) | ≥ 99.95% Cu | Maximum conductivity; for electrical/electronics |
| C12200 | DHP (Phosphorus-Deoxidised) | ≥ 99.90% Cu + Ag | General purpose; brazeable without embrittlement |
| C10800 | OFHC variant | ≥ 99.95% Cu | High-conductivity, halide-free |
C12200 is the workhorse for engineering, HVAC, chemical, and heat-exchanger tube. Always confirm alloy designation on the mill test report.
Tempers available:
| Temper | Designation | Hardness (approx.) | Best For |
|---|---|---|---|
| Annealed (Soft) | O | Low (45–65 HRF) | Bending, coiling, flaring, tight routing |
| Light-Drawn | H55 | Intermediate | Semi-rigid service with moderate bending |
| Hard-Drawn | H | High (75–95 HRF) | Rigid straight runs, maximum pressure rating |
Size range — OD from 1/4″ (6.35 mm) to approximately 4-5/8″ (117.5 mm); wall thicknesses from ~0.030″ upward.
Does NOT cover (exclusions):
| Excluded Product | Governing Standard |
|---|---|
| Plumbing water tube (types K, L, M) | ASTM B88 |
| ACR (air-conditioning & refrigeration) tube | ASTM B280 |
| Condenser/heat-exchanger tube (copper alloys) | ASTM B111 |
| Copper-nickel pipe and tube (seawater) | ASTM B466 / ASTM B467 |
| Copper drainage tube (DWV) | ASTM B306 |
| Stainless instrument tubing | ASTM A269 |
B75 is the general seamless copper tube specification. Application-specific forms (plumbing, refrigeration, condenser) each reference their own standard with product-optimised wall schedules and cleanliness requirements.
Key Requirements
B75 sets minimum requirements for seamless copper tube:
Chemical Composition
| Grade | UNS | Min. Cu + Ag (%) | Max. Impurities | Notes |
|---|---|---|---|---|
| C10200 | C10200 | 99.95 | O ≤ 0.0010% | Oxygen-free; max electrical conductivity |
| C12200 | C12200 | 99.90 | P: 0.015–0.040% | DHP; brazeable; general engineering default |
Mechanical Properties by Temper
| Temper | Tensile Strength (min.) | Yield Strength (0.5% ext., min.) | Elongation (min.) |
|---|---|---|---|
| Annealed (O) | 210 MPa (30 ksi) | 69 MPa (10 ksi) | 45% in 2″ |
| Hard-Drawn (H) | 275 MPa (40 ksi) | 240 MPa (35 ksi) | 12% in 2″ |
Dimensional Tolerances
| Dimension | Tolerance (typical) |
|---|---|
| Outside diameter (OD) | ±0.010″ (±0.25 mm) for OD ≤ 1-1/8″ |
| Wall thickness | ±10% of nominal |
Required Tests
| Test | When Required |
|---|---|
| Chemical analysis | Per heat (alloy verification) |
| Tensile test | Per heat per temper |
| Flattening test (hard-drawn) | One per lot |
| Flaring test (annealed) | One per lot |
| Hydrostatic test OR eddy-current NDE | All tubes |
| Visual and dimensional | All tubes |
Technical Details
Why Copper? Key Material Advantages
Copper combines properties that no other common engineering metal matches simultaneously:
| Property | Value | Significance |
|---|---|---|
| Thermal conductivity | ~385 W/(m·K) | Highest of structural metals; ideal for heat exchangers |
| Electrical conductivity | ~58 MS/m | Near-silver; used where conductivity matters |
| Antimicrobial | Kills Legionella, E. coli | Building water systems; hospital applications |
| Cryogenic toughness | Ductile to −270°C | LNG systems, cryogenic instrumentation |
| Jointing flexibility | Solder, braze, flare, press-fit | Versatile installation methods |
| Corrosion resistance (water) | Excellent | Potable water, cooling water, steam |
The B75 Family — Where B75 Fits Among Copper Tube Standards
ASTM maintains a family of copper tube standards, each with product-specific wall schedules and requirements:
| Standard | Product | Wall Schedule | Key Use |
|---|---|---|---|
| ASTM B75 | General seamless copper tube | OD × wall; custom | Engineering, heat transfer, instrument |
| ASTM B88 | Water tube (types K, L, M) | Prescriptive by type | Plumbing, HVAC water |
| ASTM B280 | ACR tube | Dehydrated, sealed | Air conditioning, refrigeration |
| ASTM B111 | Condenser/heat-exchanger tube | OD × BWG | Shell-and-tube heat exchangers |
| ASTM B466 | Copper-nickel pipe | NPS schedule | Seawater systems, offshore |
Jointing Methods for Copper Tube
Copper's metallurgy makes it uniquely compatible with multiple jointing methods:
| Method | Temperature | Filler | When to Use |
|---|---|---|---|
| Capillary solder | < 450°C | Sn-Sb, Sn-Cu, Sn-Ag | Plumbing, low-pressure building services |
| Brazing (silver) | > 450°C (typically 620–850°C) | BAg (silver-alloy) | High-pressure refrigerant lines, medical gas |
| Compression fitting | Ambient | None | Instrument connections; requires annealed tube |
| Flare joint | Ambient (with flare tool) | None | ACR/refrigerant; requires annealed tube |
| Press-fit (ProPress, Viega) | Ambient | None | Modern plumbing; factory-crimped O-ring seal |
For brazing C12200 tube: use BAg (silver-brazing) filler in AWS A5.8 for high-pressure gas or refrigerant service. Flux residue must be removed after brazing to prevent corrosion.
Copper vs. Stainless Steel Instrument Tubing
| Factor | Copper (B75) | Stainless (A269) |
|---|---|---|
| Thermal conductivity | ~385 W/(m·K) | ~14 W/(m·K) |
| Pressure rating (1/4″ × 0.035″) | ~150–200 bar | ~450 bar |
| Chloride resistance | Moderate | Good (TP316L) |
| Ammonia service | Not suitable | Suitable |
| Cost | Lower | Higher |
| Typical use | Low-pressure pneumatics, utilities | Process instruments, high-pressure |
Engineering Notes
Temper and alloy together define what copper tube can do — match both to the installation.
- C12200 is the default grade (DHP — Deoxidised High Phosphorus, ≥ 99.90% Cu + Ag). The phosphorus deoxidation makes it weldable and brazeable without hydrogen embrittlement risk, unlike electrolytic tough-pitch (ETP) copper. Specify C12200 for any application involving brazing or silver-alloy filler.
- C10200 (oxygen-free, OF) is for electrical and electronics applications — maximum conductivity and purity. For mechanical tubing in chemical or HVAC service, C12200 is preferred.
- Annealed (temper O) tube bends without cracking — minimum bend radius is approximately 2–3 × OD for soft-annealed copper. Ideal for coils, refrigerant lines, and routing in tight spaces. Soft tube is also required for flaring to form a leak-tight flare joint.
- Hard-drawn (temper H) tube is rigid but work-hardens permanently — do not attempt to cold-bend hard-drawn tube past its specified minimum bend radius; the work-hardened outer fibres will crack. If bending is needed post-installation, anneal locally.
- Copper is naturally antimicrobial — ionic copper suppresses Legionella and other bacteria in water systems at concentrations far below potable-water limits. This is an active hygiene advantage in hospital and pharmaceutical water distribution.
- Ammonia and acetylene destroy copper — do not use copper or copper-alloy fittings/tubes in ammonia refrigeration systems or in acetylene gas service. Ammonia forms copper-amine complexes that weaken the metal; acetylene can form explosive copper acetylide.
- High-velocity erosion-corrosion — copper in flowing water above ~1.5 m/s (5 ft/s) for soft water or ~3 m/s for harder water is at risk of erosion-corrosion at elbows and fittings. Verify velocity limits when designing copper cooling-water systems.
- Cryogenic suitability — copper retains good ductility and toughness to cryogenic temperatures (unlike ferritic steel below −29°C). Widely used for cryogenic instrumentation and LNG auxiliary systems.
Source, Edition & Status
- Publisher
- ASTM International
- Edition Year
- 2020
- Industries
- General Industry, Building Services, HVAC, Chemical Plant, Pharmaceutical
- Last Reviewed
- 2026-07-01
- Last Updated
- 2026-07-01
- Verified By
- Engineering content reviewer
- Content Status
- reviewed
- Official Link
- www.astm.org