Strut channel and fitting finishes, and which ones we supply
Five finishes cover what we quote: plain, electro-galvanized to ASTM B633 Type III SC1, hot-dip galvanized to ASTM A123 / A153, and stainless, plus powder coating to a RAL color you specify. Two finishes the catalog prints — pre-galvanized and Perma-Green — we do not quote.
Catalog no. 17 prints a FINISHES paragraph at the head of several product sections, and the lists do not agree with each other. This page transcribes each of them, sets the ASTM number against each finish, gives a coating thickness only where a file we hold actually prints one, and keeps what we supply in a table of its own.
Straight to it: what we quote · coating thickness · which series come in stainless
Both pictures are the same part number, P1026, rendered from the manufacturer STEP model in the two finishes — not photographs of stock. Plain, stainless and powder-coated parts have not been shot yet; the placeholder below says what is missing.
Which finishes we quote
Which finish is listed against which component
Each product section carries its own FINISHES paragraph and they do not match. Electro-galvanized is listed for fittings, pipe supports and electrical fittings but not for channel; pre-galvanized is listed for channel and nowhere else. “Listed” below means that section’s own FINISHES paragraph names the finish. Stainless, aluminum and fiberglass carry no finish code: a section names them in its MATERIAL note, or as a pipe-clamp suffix, and each cell says which.
Show the table — 8 rows
| Code | Finish, as printed | Standard printed against it | Channel p. 21 | Fittings p. 85 | Pipe supports p. 137 | Electrical p. 161 |
|---|---|---|---|---|---|---|
| PL | Plain | none printed | Listed | Listed | Listed | Listed |
| EG | Electro-galvanized | ASTM B633 Type III SC1 | not listed | Listed | Listed | Listed |
| HG | Hot-dipped galvanized | differs by page — see the page columns | Listed — ASTM A123 | Listed — ASTM A123 or A153 | Listed — ASTM A123 or A153 (hardware) | Listed — ASTM A123 or A153 |
| PG | Pre-galvanized | ASTM A653 G90 | Listed | not listed | not listed | not listed |
| GR | Perma-Green II | none printed | Listed | Listed | Listed | Listed |
| — | Stainless steel | none printed | not listed | Listed as a material, consult factory | Listed as a material, consult factory; pipe-clamp suffix SS or ST | not listed |
| — | Aluminum | none printed | not listed | Listed as a material, consult factory | Pipe-clamp suffix AL | not listed |
| — | Fiberglass | none printed | not listed | Listed as a material, consult factory | not listed | not listed |
The paint is printed two ways and we do not pick a side: p. 21 prints Perma Green II and p. 85, 137, and 161 print Perma-Green II. For channel, stainless and aluminum are not in the p. 21 finish list; the p. 24 selection chart prints them series by series — see which series come in stainless or aluminum. Source: Unistrut® General Engineering Catalog no. 17, p. 21, 85, 137, and 161 · Verified 2026-09-27
What we quote
This is the whole of it. Everything in this table is made to order by a contract manufacturer against the catalog number, and the row that has no catalog counterpart is marked as such rather than dressed up as one.
| We quote | Worked to | Catalog counterpart |
|---|---|---|
| Plain | Uncoated steel | PL, p. 21, 85, 137, and 161 |
| Electro-galvanized (EG) | ASTM B633 Type III SC1 | EG, p. 85, 137, and 161 |
| Hot-dip galvanized (HDG) | ASTM A123 / A153 | HG, p. 21, 85, 137, and 161 |
| Stainless | 304 or 316, grade confirmed at quotation | No finish code; listed as a material on p. 85 and 137; pipe-clamp suffix SS or ST, p. 137 |
| Powder coating | A RAL color you specify | none — not in the catalog |
The first two columns are our supply, not a catalog figure. Fitting plate: About 0.23 in. (5.8 mm) base steel before coating; a hot-dip galvanized part measures thicker; catalog reference part 1/4 in. (6.4 mm). Steel grade confirmed at quotation. Supply terms as stated on our Contact page. Not quoted at present: Pre-galvanized (PG) · Perma-Green (GR) · Aluminum · Fiberglass. Catalog counterpart column: Unistrut® General Engineering Catalog no. 17, p. 21, 85, 137, and 161 · Verified 2026-09-27
Quote one of them directly: plain · electro-galvanized · hot-dip galvanized · stainless · powder coating. The form opens with that finish already chosen. There is no link for PG or GR, on this page or on any part page, because we do not quote them.
Coating thickness
The catalog puts a standard against most finishes but a thickness against none. A minimum is printed below only where a file we hold prints one — the standard itself for electro-galvanizing, a third-party summary for the hot-dip hardware standard — and the rest are left blank on purpose.
Show the table — 12 rows
| Standard | Class | Minimum coating thickness | What the class covers | Printed in |
|---|---|---|---|---|
| ASTM B633-13 | SC 1 | 0.20 mils (5 µm) | Service condition: mild. Classification Fe/Zn 5. The class the catalog specifies. | ASTM B633-13 Table 1, p. 2 — the standard itself |
| ASTM B633-13 | SC 2 | 0.31 mils (8 µm) | Service condition: moderate. Classification Fe/Zn 8. | ASTM B633-13 Table 1, p. 2 — the standard itself |
| ASTM B633-13 | SC 3 | 0.47 mils (12 µm) | Service condition: severe. Classification Fe/Zn 12. | ASTM B633-13 Table 1, p. 2 — the standard itself |
| ASTM B633-13 | SC 4 | 0.98 mils (25 µm) | Service condition: very severe. Classification Fe/Zn 25. | ASTM B633-13 Table 1, p. 2 — the standard itself |
| ASTM A153/A153M | Class A | 3.40 mils (86 µm) average of specimens tested; 3.10 mils (79 µm) any individual specimen | Castings: Malleable Iron, Steel | A third-party summary chart of the standard — secondary source |
| ASTM A153/A153M | Class B-1 | 3.40 mils (86 µm) average of specimens tested; 3.10 mils (79 µm) any individual specimen | Rolled, Pressed and Forged articles (except those which would be included under Class C and D): 3/16 in. (4.76 mm.) and over in thickness and over 15 in. (381 mm.) in length | A third-party summary chart of the standard — secondary source |
| ASTM A153/A153M | Class B-2 | 2.60 mils (66 µm) average of specimens tested; 2.10 mils (53 µm) any individual specimen | Rolled, Pressed and Forged articles (except those which would be included under Class C and D): under 3/16 in. (4.76 mm.) in thickness and over 15 in. (381 mm.) in length | A third-party summary chart of the standard — secondary source |
| ASTM A153/A153M | Class B-3 | 2.20 mils (56 µm) average of specimens tested; 1.90 mils (48 µm) any individual specimen | Rolled, Pressed and Forged articles (except those which would be included under Class C and D): any thickness and 15 in. (381 mm.) and under in length | A third-party summary chart of the standard — secondary source |
| ASTM A153/A153M | Class C | 2.10 mils (53 µm) average of specimens tested; 1.70 mils (43 µm) any individual specimen | Fasteners over 3/8 in. (9.52 mm.) in diameter and similar articles. Washers 3/16 in. (4.76 mm.) and 1/4 in. (6.35 mm.) in thickness | A third-party summary chart of the standard — secondary source |
| ASTM A153/A153M | Class D | 1.70 mils (43 µm) average of specimens tested; 1.40 mils (36 µm) any individual specimen | Fasteners in 3/8 in. (9.52 mm.) and under in diameter, Rivets, Nails and similar articles. Washers under 3/16 in. (4.76 mm.) in thickness | A third-party summary chart of the standard — secondary source |
| ASTM A123 | none named | not published here — no file we hold prints one | The catalog names the standard without a class | nothing on file |
| ASTM A653 | G90 | not published here — no file we hold prints one | The designation the catalog prints, p. 21 | nothing on file |
The catalog names one ASTM B633 class, SC1; the others are shown for context; a heavier class is confirmed at quotation. ASTM B633 prints its classes in micrometers only; the mils in front are computed from them (1 mil = 25.4 µm) and rounded to two places, as the ASTM A153/A153M chart prints its own. The ASTM A153/A153M figures are a secondary source: they come from a single-page summary chart of that standard, not from the standard itself, and the catalog does not say which of its classes applies to a given part. No figure is printed for ASTM A123 and ASTM A653, because nothing we hold prints one. Sources: ASTM B633-13 Table 1; ASTM A153/A153M summary chart · Verified 2026-09-27
Which series come in stainless or aluminum
Finish is a choice on most parts; stainless and aluminum are not. The channel selection chart prints a stainless gauge or an aluminum thickness for some series and a dash for the rest, and that is the whole published range.
Show the table — 9 rows
| Series | Steel gauge | Stainless gauge | Aluminum thickness |
|---|---|---|---|
| P1000 | 12 ga | 12 ga | 0.109 in. (2.8 mm) |
| P1100 | 14 ga | 14 ga | — |
| P2000 | 16 ga | — | — |
| P3000 | 12 ga | — | — |
| P3300 | 12 ga | 12 ga | — |
| P4000 | 16 ga | 16 ga | 0.078 in. (2.0 mm) |
| P4100 | 14 ga | — | — |
| P5000 | 12 ga | — | — |
| P5500 | 12 ga | — | 0.109 in. (2.8 mm) |
A dash is the catalog’s own dash. The chart lists single channels only; back-to-back combinations are not in it. No ASTM number is printed for the stainless anywhere in our source, so none is printed here. Source: Unistrut® General Engineering Catalog no. 17, p. 24, Channel Selection Chart · Verified 2026-09-27
Where finishes belong
Where each finish belongs
- Plain (PL)
- Plain, uncoated steel. For painting or powder coating after assembly, or dry enclosed runs.
- Electro-galvanized (EG)
- Zinc plating to ASTM B633 Type III SC1. Smooth bright silver. Indoor and dry service.
- Hot-dip galvanized (HG)
- Hot-dip galvanized after forming. Coats the cut edges and the inside of the holes. Visible spangle, heavier edge build-up. Outdoor, wet and coastal service.
- Pre-galvanized (PG)
- Strip coated before forming. The cut ends and the punched edges are bare — that is normal for PG and is why it is an indoor finish. Listed for channel only, and not quoted by us.
- Perma-Green (GR)
- A painted finish, not a plating, so treat cut edges and scratches as bare steel. Not quoted by us.
The first three notes are the wording published on our part pages, carried here unchanged so one description does not fork into two. The last two are published here only: the part pages name PG and GR in one line of small print and link back to this page, because a finish we do not quote must not carry a quote button. The finish lists they describe are catalog p. 21 (channel) and p. 85 (fittings). No corrosion-category rating, service life or salt-spray hour is claimed on this page, because we hold no source for one · Verified 2026-09-19
Mixing finishes in one assembly
The choice that matters is not a part’s finish on its own but the pairing. Match the fitting finish to the channel: a thinner zinc coating (EG) or bare steel (PL) will show rust well before hot-dip galvanized channel does, so a mixed run is only as durable as its least protected part — the bolt and the channel nut included.
Wording carried unchanged from the Finishes section of Strut channel sizes, where it has been published since 2026-07-14. Source: Unistrut® General Engineering Catalog no. 17, p. 21 and 85 for the finish lists themselves · Verified 2026-09-19
Suffixes and paperwork
Special-material suffixes on pipe clamps
Pipe clamps carry a second, separate system: a material suffix added to the part number. It applies only to the clamp series named in the catalog table’s title, listed under the table.
Show the table — 5 rows
| Material | Suffix | Example |
|---|---|---|
| Steel Strap, Everdur Hardware | E | P1109 E |
| Copper Coated Steel Strap & Hardware | CC | P1109 CC |
| Aluminum | AL | P1109 AL |
| Stainless Steel 304 or 316 | SS or ST | P1109 SS |
| Plastic Coated Steel Straps | PC | P1109 PC |
The table title limits it to the P1109, P1211, P1425, and P2024 series; every example the catalog prints uses P1109. These are part-number suffixes, not finish codes. Of these we quote only the SS or ST suffix (Stainless Steel 304 or 316). Source: Unistrut® General Engineering Catalog no. 17, p. 137 · Verified 2026-09-27
Asking for the paperwork
Name the documents in the inquiry, not after the purchase order. Mill certificate on request; coating-thickness readings and any third-party test are arranged per order. What we can supply against a given order is confirmed at quotation, and what we cannot is said in the same sentence.
There is no standing certificate package behind this page. Documents still to be obtained include the A1011 HSLAS GR 45 mill certificate and the measured coating thickness after hot-dip galvanizing. Nothing on this page should be read as a certificate already in hand · Verified 2026-09-19
What we do not publish
What we do not publish, and why
No load figure appears on this page or anywhere else on this site as our own. The catalog’s design load data is published under conditions it states itself: “All parts drawings illustrate only one application of each fitting”, and design load data “is based on the ultimate strength of the connection” with a stated safety factor, “unless otherwise noted” (p. 85). The 90° fitting tables on p. 89 are tighter still — they hold only “when used in position shown”, with both ends of the beam supported, and with a P1010 nut and a 1/2 in. bolt.
Two consequences we will not paper over. First, a rating printed against a reference part in one illustrated position is not the capacity of your assembly; that is an engineering question about the whole support, not about one part number. Second, what we quote is a candidate substitute made to order against the catalog number, so the reference part’s published figures do not travel with it. If your submittal needs numbers, say so and we will price the testing: measured coating thickness, material certificate, and a third-party load test on the actual parts, arranged per order and confirmed at quotation.
Conditions quoted from Unistrut® General Engineering Catalog no. 17, p. 85 and p. 89. The candidate-substitute position and the outstanding test list are our own · Verified 2026-09-19
What this page does not publish
- No ASTM number for the stainless. The catalog names the grades, in the pipe-clamp suffix table, and stops there. We do not hold ASTM A240, so we do not cite it.
- No A123 coating grade. The catalog names A123 without a grade, and the grade-by-thickness table is not in our files.
- No film thickness or salt-spray figure for powder coating. It is a capability we have, not a specification we have measured.
- No price difference in numbers. Price is confirmed at quotation. The lead time does not change by finish.
- No load figure of any kind. See what we do not publish for the catalog’s own conditions and for what we can arrange instead.
- No corrosion category. Coastal, desert and cleanroom are selling words; the only service statements on this page are the catalog’s own.
Quote
Where to go next
- Strut channel sizes — every series, and which finishes the catalog lists for channel rather than for fittings.
- 41 mm metric strut channel — the same sections under their metric names, plus lengths and the hole pattern.
- Pipe support parts — where the pipe-clamp material suffixes above are actually used.
- All fittings · clamps · channel nuts — each family’s own finish selector.
Frequently asked questions
What does EG mean on a strut fitting?
EG is electro-galvanized. Catalog no. 17 specifies it as ASTM B633 Type III SC1 on three separate pages, p. 85 for fittings, p. 137 for pipe supports, and p. 161 for electrical fittings. SC1 is the mild service condition in ASTM B633-13; its minimum coating thickness is in the coating thickness table on this page.
Is hot-dip galvanized the same as pre-galvanized?
No, and the difference shows up at the cut ends. Pre-galvanized channel is rolled from strip that was coated first, to ASTM A653 G90, so every cut end and punched hole edge is bare steel. Hot-dip galvanized is dipped after the part is formed, to ASTM A123, so it coats the cut edges and the inside of the holes. We quote hot-dip galvanized; we do not currently quote pre-galvanized.
Can you powder coat strut channel and fittings?
Yes, to a RAL color you specify. Powder coating is not in catalog no. 17, so it has no catalog code and no catalog counterpart on this page: it is our own capability, confirmed 2026-09-19. Which parts, which color and film build are settled at quotation. We publish no film thickness or salt-spray figure because we have not measured one.
Which strut channel series come in stainless steel?
Four of the nine series in the p. 24 channel selection chart print a stainless gauge: P1000, P1100, P3300, and P4000. The gauge for each is in the stainless table on this page. P2000, P3000, P4100, P5000, and P5500 print no stainless gauge. The catalog gives no ASTM number for the stainless itself, so we do not print one either.
Get a finish quoted
Finish is priced per mill, per volume and per part, so there is no list price to publish. Tell us the four lines below and we come back with what we can coat, what standard we work to, and what documentation we can supply with it. We reply within one business day (Asia/Shanghai, UTC+8).
- The finish — plain, electro-galvanized, hot-dip galvanized, stainless, or powder coating with the RAL color
- The part numbers, or the family
- Quantity, and the destination
- Whether a coating-thickness or material certificate has to come with it
No minimum order · 5–7 business days ex-factory · Reply within one business day (Asia/Shanghai, UTC+8) · Finishes: plain, EG, HDG, stainless
Powder coating and the RAL color are settled in the quote — they are not in catalog no. 17 and we publish no film thickness. Prefer email? Write to contact@channelstrut.com.
Trademarks and who we are
Unistrut, B-Line, Superstrut, Power-Strut and Haydon, and the part numbers published under them, are trademarks or trade names of their respective owners. ChannelStrut is not affiliated with, authorized by, endorsed by or a distributor for any of them. Those brand names and part numbers are used here only to identify the products referred to.
ChannelStrut is run by Alex, a hardware sourcing specialist based in Fujian, China. We do not manufacture these parts — we source them from the mills that produce them. More on how the data is built: About.