ERW carbon steel mechanical tubing produced from precoated steel sheet — galvanized, galvannealed, aluminum-coated, or 55% Al-Zn alloy-coated. Six Types covering both precoated and post-galvanized options, manufactured to ASTM A787/A787M-22.
A787 is the spec to call out when your application needs the dimensional precision of A513 mechanical tubing plus an integrated corrosion-resistant coating on both inside and outside surfaces. Outdoor agricultural equipment, fence posts, hand rails, conveyor frames in wet environments, fitness equipment headed for outdoor use, and OEM components where post-paint or post-galvanizing isn't economical — A787 covers them.
| Type | Code | Description |
|---|---|---|
| Type 1 | AWAC | Aluminum-coated mechanical tubing (precoated) |
| Type 2 | AWG | Galvanized mechanical tubing (precoated, zinc) |
| Type 3 | AWPG | Post-hot-dipped galvanized — bare tube galvanized after welding |
| Type 4 | AWGA | Galvannealed (zinc-iron alloy-coated, precoated) |
| Type 5 | AWGZ | 55% Aluminum-Zinc alloy-coated (precoated) |
| Type 6 | AWZAM | Zinc-Aluminum-Magnesium alloy-coated (precoated) |
Per ASTM A787/A787M-22 Section 3. The ordered wall thickness includes both the base metal and the metallic coating (Section 4.1).
| Grade | Carbon | Manganese | P, max | S, max |
|---|---|---|---|---|
| MT1010 | 0.05 – 0.15 | 0.30 – 0.60 | 0.035 | 0.035 |
| MT1015 | 0.10 – 0.20 | 0.30 – 0.60 | 0.035 | 0.035 |
| MTX1015 | 0.10 – 0.20 | 0.60 – 0.90 | 0.035 | 0.035 |
| MT1020 | 0.15 – 0.25 | 0.30 – 0.60 | 0.035 | 0.035 |
| MTX1020 | 0.15 – 0.25 | 0.70 – 1.00 | 0.035 | 0.035 |
Per ASTM A787/A787M-22 Table 1. Standard grades 1008–1021 also available per Table 2.
Numbers from ASTM A787/A787M-22, filtered to MMC's production size ranges.
| OD Range | Outside Diameter ± |
|---|---|
| ½″ to 1⅛″, incl. | 0.0035″ |
| Over 1⅛″ to 2″, incl. | 0.005″ |
| Over 2″ to 2½″, incl. | 0.006″ |
| Over 2½″ to 3″, incl. | 0.008″ |
| Over 3″ to 3½″, incl. | 0.009″ |
Per ASTM A787/A787M-22 Table 5. All wall thickness tolerances include base steel plus the coating on inside and outside surfaces.
| OD Range | Wall · Plus | Wall · Minus |
|---|---|---|
| ½″ to 1″, incl. | 0.005″ | 0.007″ |
| Over 1″ to 1 15⁄16″, incl. | 0.004″ | 0.008″ |
| Over 1 15⁄16″ to 3¾″, incl. | 0.003″ | 0.009″ |
| Over 3¾″ to 4½″, incl. | 0.003″ | 0.009″ |
Per ASTM A787/A787M-22 Table 3. Other gages (14 BWG–7 BWG) follow the same OD-range structure with progressively wider tolerances. Post-hot-dipped galvanized (Type 3) wall thickness is by agreement (Section 6.2).
Mechanical tubing — Type 1 hot-rolled and Type 2 cold-rolled. Grades 1008–1020.
Cold-formed structural HSS. Grade B and Grade C. The bridge-and-building spec.
Cold-formed structural tubing from precoated sheet. Galvanized inside and out.
ASTM A787 is the standard specification for ERW carbon steel mechanical tubing produced from precoated steel sheet — galvanized, galvannealed, aluminum-coated, or 55% Al-Zn alloy-coated — plus a post-galvanized option. Major Metals manufactures A787 tubing to ASTM A787/A787M-22.
Type 1 (AWAC) aluminum-coated · Type 2 (AWG) galvanized zinc, precoated · Type 3 (AWPG) post-hot-dipped galvanized after welding · Type 4 (AWGA) galvannealed zinc-iron · Type 5 (AWGZ) 55% aluminum-zinc alloy · Type 6 (AWZAM) zinc-aluminum-magnesium alloy. All precoated except Type 3.
Precoated Types run already-coated strip through the mill, so both inside and outside surfaces carry the coating and dimensions stay tight. Type 3 galvanizes the bare tube after welding — a heavier dip coating, with wall thickness by agreement per Section 6.2.
When you need A513-style mechanical precision plus built-in corrosion protection inside and out — outdoor agricultural equipment, fence posts, hand rails, conveyor frames in wet environments, and OEM parts where post-paint or post-galvanizing isn't economical.
Yes. Per ASTM A787/A787M-22 Section 4.1, the ordered wall thickness includes both the base metal and the metallic coating on inside and outside surfaces.
Low-carbon grades per ASTM A787/A787M-22 Table 1, with standard grades 1008–1021 also available per Table 2.
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