PG30 30×30 mm Two Slot Type B Aluminium Strut Profile Symmetric T-Slot Extrusion for Corner Posts

OEM / ODM Available Free Sample Available ISO 9001:2015 EN 755-9 RoHS REACH

30 x 30 mm Type B two slot PG30 aluminium strut profile in 6063-T5 with 8.2 mm grooves on opposite faces. A symmetric section with the centroid on the geometric centre, for corner posts and uprights.

Wholesale Price $1.70 - $2.85 / m per m

Material	Aluminium
Alloy Grade	6063-T5
Temper	T5
Section Size	30 x 30 mm
Slot	2 x 8.2 mm groove, 6 mm mouth, opposite faces, 23 mm pitch, M8
Length	6 m stock, cut to drawing to +/-0.5 mm
Tolerance	EN 755-9 / GB/T 6892, wall +/-0.15 mm
Surface	Mill finish / clear anodised / black anodised
MOQ	500
Lead Time	15-25 days after deposit for mill finish
Loading Port	Shanghai / Ningbo
Supply Ability	600 t per month
Payment Terms	T/T 30% deposit + 70% before shipment \| L/C at sight
Trade Terms	FOB \| CIF \| EXW
Certifications	ISO 9001:2015 \| EN 755-9 \| RoHS \| REACH

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Structural framing · PG30 Type B

A 30 x 30 mm Type B two-slot strut profile is a square aluminium extrusion with a T-slot on two of its four faces, arranged so that the two slots face each other. That single detail — opposite rather than adjacent — makes the section symmetric about both face centrelines, and it is the whole reason to specify Type B. The groove is 8.2 mm with a 6 mm mouth on a 23 mm pitch, so it takes 30-series M8 hardware. The centre bore is Ø10 mm tapped M12, the corner holes are Ø4.5 mm tapped M6, and the wall is 2.2 mm at the flange and 8 mm through the web. We extrude it in 6063-T5 and supply it cut, drilled, tapped or machined.

Symmetry sounds like a cosmetic property until the member is used as an upright. A column loaded in compression fails by buckling, and buckling is governed by where the load sits relative to the centroid of the section. On a symmetric section the centroid is on the geometric centre, so a load applied at the centre of the end face goes straight down the axis and nothing bends. On an asymmetric section the centroid is offset, the same load is eccentric, and the member picks up a bending moment it was never designed for. That difference is worth roughly a third of the buckling capacity, and it costs nothing to get right.

30 x 30 Type B section: slots on two opposite faces, symmetric about both centrelines, 23 mm pitch and an M12 centre bore.

Why symmetry is a structural property, not a detail

Every section has a centroid, and every load has a line of action. If the two coincide the member is in pure compression and behaves predictably. If they do not, the offset multiplied by the load becomes a bending moment, and the member has to resist bending as well as compression. That is how a column that looked fine on paper fails at two thirds of the load it was supposed to carry.

Type B is symmetric about both face centrelines, so its centroid is exactly on the geometric centre. A load applied at the centre of the end face is concentric. The section is also equally stiff in both directions, so it does not matter which way round the upright is installed — an advantage on site, where the person assembling the frame is rarely the person who drew it.

Property	Type B (this section)	Type A
Slot positions	Two opposite faces	Two adjacent faces
Centroid	On the geometric centre	Offset towards the closed corner
Stiffness, both axes	Equal	Not equal
Concentric axial load	Yes, at the end face centre	No, unless offset
Buckling capacity	Predictable, symmetric	Reduced by eccentricity
Best as	Corner post, upright, leg	Edge rail, seal carrier
Slot groove	8.2 mm, 6 mm mouth	8.2 mm, 6 mm mouth
Weight	approx. 0.86 kg/m	approx. 0.86 kg/m

The eccentricity trap: if a Type A member is used as an upright and loaded at the geometric centre of its end face, the load is eccentric by a few tenths of a millimetre. That is small, but on a 2 m column it is the difference between a straight post and one that bows under load. If a two-slot upright has to carry compression, specify Type B.

Assembling a post that takes parts on two sides

The obvious use of a Type B upright is a post that has something bolted to it on two opposite sides — a panel on one face and a shelf bracket on the other, or two panels back to back. Because the slots are directly opposed, a fixing on one side can be reached from the other, which makes assembly and later adjustment far easier than on an asymmetric section. The order of assembly still matters.

Pre-load the nuts before the frame goes up With the slots opposed, you can slide a nut into each slot from the end while the member is still on the bench, then stand the post up. Trying to feed nuts into a vertical member after the frame is built is the slowest part of the job.
Fix the more heavily loaded side first Tighten the panel side before the bracket side. Once the first side is tight the member cannot rotate, so the second side can be set without the post turning away from the driver.
Check square before final torque A symmetric post is easy to get plumb but hard to twist back afterwards. Set the frame square with the fixings just nipped, then torque to the specified figure.
Leave one slot clear on long posts On a post over 1.5 m, keep one of the two slots free for a mid-height tie or a levelling adjustment. Filling both slots at the top and bottom leaves nothing to correct with later.

The alignment trap when Type A and Type B are used together

Frames often need both an edge rail (Type A, for its closed face) and an upright (Type B, for its symmetry). The two sections have identical outside dimensions, identical grooves and identical weight, so a mixed delivery looks perfectly consistent — and that is exactly why the error goes unnoticed. The slots do not line up. On a Type B member the slots are on opposite faces; on a Type A member they are on adjacent faces. Where the two meet, one member’s slot faces a closed face on the other, and a fixing that was meant to pass through both cannot be made.

The rule is simple: make the change of section at a joint, never mid-member, and always through a bracket, a connector or a plate that is dimensioned for both. Never assume that a 30 x 30 bracket will line up two 30 x 30 members without checking which type each one is.

The Type A section this one is often confused with, and the R90 quarter round version for frames that must have no sharp external edges.

Frequently asked questions

How is Type B different from Type A?

Only in the arrangement of the two slots. Type B has them on opposite faces and is symmetric about both face centrelines; Type A has them on adjacent faces and leaves a closed corner. Outside dimensions, groove, pitch and weight are identical.

Is Type B always better than Type A?

No. Type B is better where the member carries compression or has to behave the same way in both directions, which is why it suits uprights. Type A is better where a closed face is needed for a seal, a datum or a dowel, which is why it suits edge rails.

Can I use it as a beam rather than a post?

Yes, and it is the better choice for a beam where the load direction is not yet known, because it is equally stiff in both axes. For a beam with a known load direction a section with more material further from the neutral axis will be lighter for the same stiffness.

Does the 8.2 mm groove take M6 as well as M8?

The groove takes 30-series M8 nuts and hammer-head bolts. M6 is used on the Ø4.5 mm corner holes, not in the slot. Using an undersized nut in the slot lets the nut rotate and the joint will not stay tight.

What length and tolerance do you supply?

Standard stock is 6 m, cut to the drawing at +/-0.5 mm per piece, deburred and bagged by assembly. Where a frame has to assemble square, give us a cut list rather than a total length.

Send the post height and the load, get a section check

Tell us the upright height, the compression load and what hangs off each side. We will confirm the section and the buckling margin, then quote cut lengths, machining and FOB pricing.

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