PFC Steel Explained: What Is a Parallel Flange Channel?
PFC steel — the parallel flange channel — is a C-shaped structural steel section with two flat, parallel flanges joined by a vertical web. It is one of the most useful sections in UK construction, working as a lintel, an edge beam, a purlin or a trim where a flat outer face is needed. This guide explains what PFC steel is, the common sizes and weights, the grades it comes in, how it differs from an RSJ, and where to buy it cut to size.
What Is PFC Steel?
PFC stands for parallel flange channel — a hot-rolled structural steel section shaped like a "C" or "U". It has a vertical web with two horizontal flanges projecting from one side, and crucially those flanges are parallel (the same thickness from root to toe) rather than tapered. That flat, parallel inner face makes bolting, fixing and seating far easier than the older tapered-flange channel. PFC sizes and properties are set out in BS EN 10365 (which superseded the dimensions formerly listed in BS 4-1), so a "150 x 75 PFC" is the same section whichever UK stockholder you buy it from.
PFC vs RSJ: What's the Difference?
An RSJ (universal beam) is an I- or H-shaped section with a flange on both sides of the web, giving symmetric strength for spanning loads — it is the default for beams over knocked-through openings. A PFC has a flange on one side only, so it is less efficient as a pure spanning beam but ideal where you need a flat back against a wall, floor or another section. Common choices: use an RSJ where the beam sits within the structure and carries heavy floor or wall loads; use a PFC for lintels, stair stringers, edge/trimmer beams, and anywhere the open channel or flat face suits the detail. Channels are also frequently bolted back-to-back to form a stronger box-like member.
PFC vs RSC (Tapered Flange Channel)
You may still see the older RSC (rolled steel channel) referenced. The difference is the flange: an RSC has tapered flanges (thicker at the root, thinner at the toe), while a PFC has parallel flanges of constant thickness. Parallel flanges are easier to drill, bolt and connect because washers and plates sit flat, which is why PFC has become the modern standard and RSC is largely superseded for new structural work.
Common PFC Sizes and Weights
PFC is described as depth × flange width × weight per metre — for example a "200 x 90 x 30" is 200mm deep, 90mm wide, and weighs 30 kg per metre. The table below lists popular UK sizes to BS EN 10365. Heavier sections per metre mean a thicker web and flange, and a higher load capacity.
| Size (D × B) | Mass (kg/m) | Typical use |
|---|---|---|
| 100 × 50 | 10.2 | Light trims, small lintels, frames |
| 125 × 65 | 14.8 | Light lintels, secondary members |
| 150 × 75 | 17.9 | Lintels, edge beams |
| 180 × 75 | 20.3 | Edge beams, purlins |
| 200 × 75 | 23.4 | General structural |
| 200 × 90 | 29.7 | Beams, back-to-back members |
| 230 × 90 | 32.2 | Heavier lintels and beams |
| 260 × 90 | 34.8 | Floor edge beams |
| 300 × 90 | 41.4 | Primary framework |
| 300 × 100 | 45.5 | Heavy beams |
| 430 × 100 | 64.4 | Long-span / heavy duty |
Always size structural steel from a structural engineer's calculation for your specific loads and span — the table is a guide to what's available, not a substitute for design.
What Grade Is PFC Steel?
PFC is normally supplied in S355 structural steel (355 N/mm² yield strength), the modern default for hot-rolled sections, with some smaller sizes available in S235. S355 gives a high strength-to-weight ratio and excellent weldability without preheat at typical thicknesses. For how the structural grades compare, see our guide to S275 vs S355 steel, and our steel grades and standards reference.
Common Uses for PFC
The flat-backed C-profile makes PFC one of the most versatile sections on a job. Typical uses include lintels over door and window openings, edge and trimmer beams around floor openings and stairwells, purlins and rails in light steel frames, stair stringers, and trims or kerbs where a neat flat face is wanted. Channels are often used back-to-back (two PFCs bolted web-to-web or toe-to-toe) to make a stronger symmetric member, and in fabrication for trailer beds, frames and machine bases.
Buy PFC Steel at Rackerman
Rackerman supplies parallel flange channel (PFC) in S355, cut to size, plus mild steel channel in S275 for general fabrication. Browse the full metal sections range — angles, box section, flat and round bar — and our RSJ steel beams and columns when you need an I-section instead. Not sure which to choose? Our guides on what an RSJ is and how much a steel beam costs will help.
Browse steel sections at Rackerman →
Frequently Asked Questions
What is PFC steel?
PFC steel is a parallel flange channel — a hot-rolled, C-shaped structural section with a vertical web and two flat, parallel flanges on one side. It is used for lintels, edge beams, purlins and frames, and is defined by BS EN 10365 so sizes are consistent across UK suppliers.
What does PFC stand for in steel?
PFC stands for Parallel Flange Channel. The "parallel" refers to the flanges being a constant thickness from root to toe, unlike the older tapered-flange channel (RSC). The parallel face makes bolting and fixing flat connections much easier.
What is the difference between PFC and RSJ?
An RSJ (universal beam) is an I/H-section with flanges on both sides of the web, best for spanning beams. A PFC is a C-section with a flange on one side only, suited to lintels, edge beams and details needing a flat back. RSJs carry heavier spanning loads; PFCs suit edge and trim applications and bolt neatly back-to-back.
What is the difference between PFC and RSC?
Both are steel channels. A PFC has parallel flanges of constant thickness; an RSC (rolled steel channel) has tapered flanges that are thicker at the root. PFC is the modern standard because its flat parallel faces make drilling, bolting and connecting easier; RSC is largely superseded.
What grade is PFC steel?
PFC is normally supplied in grade S355 (355 N/mm² yield strength), with some smaller sizes available in S235. S355 offers a high strength-to-weight ratio and good weldability, making it the standard choice for structural channel in the UK.
How are PFC sizes measured?
PFC is described as depth × flange width × mass per metre — for example 200 × 90 × 30 is 200mm deep, 90mm wide and 30 kg per metre. Sizes run from 100 × 50 (about 10 kg/m) up to 430 × 100 (about 64 kg/m) to BS EN 10365.
Can PFC be used as a lintel?
Yes — PFC is commonly used as a steel lintel over door and window openings, where its flat back sits neatly against the masonry. The correct size must come from a structural engineer's calculation for the opening width and load above it.
Can you weld parallel flange channel?
Yes. S355 and S275 channel weld readily with standard equipment and without preheat at typical thicknesses, which is why PFC is widely used in fabrication. Follow your fabricator's weld procedure and any structural engineer's connection details.
Is PFC stronger than angle or box section?
It depends on the orientation and load. PFC offers good bending strength about its major axis for its weight, more than an equivalent angle, while box (hollow) section is stiffer in torsion. Choose the section to suit the loading — your engineer will specify it.
Can PFC be cut to size?
Yes. Rackerman supplies PFC cut to your required lengths, so you receive the channel ready to install rather than a full stock length. Provide your cutting list at checkout or on enquiry.