Products & Systems / Structural GRP profiles
Pultruded GRP box sections
GRP box sections.
Resolve the joint.
Square and rectangular GRP hollow profiles for posts, rails and fabricated frames. Match the section geometry to the load, connection access and assembly requirements.
Reference square profiles
Compare the walls.
Confirm the exact section.
The VGRP-DS-36 reference lists these square box sections. The table identifies nominal dimensions and mass; use current product information for final selection and design.
| External size × wall thickness | Listed mass (kg/m) |
|---|---|
| 25 × 25 × 3 | 0.46 |
| 31.8 × 31.8 × 3 | 0.68 |
| 38 × 38 × 5 | 1.20 |
| 38.1 × 38.1 × 3.2 | 0.72 |
| 44 × 44 × 6 | 1.67 |
| 51 × 51 × 3.25 | 1.10 |
| 51 × 51 × 6.35 | 2.10 |
| 60 × 60 × 4.5 | 1.80 |
| 100 × 100 × 4 | 2.75 |
The reference also lists a rectangular section. Request its dimensioned drawing to confirm the wall arrangement and orientation. For every profile, confirm tolerances, resin, material grade, colour and supply length. The listed mass describes self-weight, not load capacity.
Design around the member role
Post, rail or frame.
Set the design conditions.
The same shape can serve different purposes. Identify the member action and its restraint before selecting dimensions or applying load information.
Posts & uprights
Define the applied actions, unrestrained length and base connection. Review stability, movement and load transfer into the supporting structure.
Rails & horizontal members
Identify span, loading direction and end conditions. Check deflection and the behaviour of the joints at each end.
Frame assemblies
Consider the connected arrangement, bracing and erection state. Member properties alone do not establish the stiffness of the frame.
For guarding, use the complete SafeClamp® handrail system route and its project requirements. A hollow profile on its own does not establish guardrail performance.
Connections to hollow profiles
Reach the fastener.
Control the local load.
Design the joint so it can be fabricated, assembled and inspected. Account for the hollow interior and the forces introduced into the profile walls.
Through-bolts
Show the bolt path, washers and any required internal detail. Review local wall effects and the specified tightening method; avoid assuming an unsupported wall can accept any clamping force.
Internal access
Confirm how nuts, inserts or other components are positioned and retained. Coordinate access before the member ends or adjacent assemblies become inaccessible.
Hole layout
Specify hole sizes, spacing and edge distances. Check the remaining section and local bearing at the connection.
Bases & end details
Define how reactions pass through the end connection. Include contact surfaces, fixings, supporting substrate and installation tolerances.
Ends & moisture
Agree end protection, drainage and exposure details appropriate to the environment. Do not assume a hollow section will remain dry in service.
Where a detail requires inserts, sleeves or reinforcement, specify them through the accepted design. These are connection decisions, not automatic additions to every box section.
Assembly and site interfaces
Schedule the parts.
Plan the access.
Coordinate the fabrication around the installation sequence. The connection must be accessible when the members come together and inspectable before handover.
Before fabrication
Provide member lengths, holes, orientation, end details and revision. Confirm compatibility with adjoining fittings and components.
At installation
Check support locations and the delivered member identification. Resolve changes through the design process before cutting or drilling on site.
For the asset record
Keep the final arrangement, materials, connections and inspection information with the structure.
Evidence for the selected profile
Confirm the properties.
Complete the design brief.
Request the current material designation and section properties for the selected profile. Include the connection arrangement and exposure conditions in the review.
Material grade
Use the BS EN 13706 series as the relevant pultruded-profile specification reference. Confirm the actual product declaration and grade.
Section information
Obtain dimensions, tolerances and the properties for the required axes. Rectangular sections require particular attention to orientation and wall arrangement.
Service conditions
Identify chemicals, temperature, moisture and fire requirements. Include metallic fittings and any exposed cut surfaces in the material review.
Send the member and joint together.
Include the layout, actions, restraint, base detail and required assembly format.
For a defined materials order, use GRP Express. For a fabricated assembly or design coordination, send the brief to Vital.
Questions about box sections.
Are box sections solid?
No. These profiles have a hollow interior. The wall geometry and connection arrangement need to be considered in the design.
Can I bolt through both walls?
Use a designed connection detail that addresses local wall behaviour, fastener layout and tightening. Confirm any internal components and assembly access.
Are square and rectangular profiles interchangeable?
No. Confirm geometry, section properties and orientation for the actual member. Similar external dimensions do not establish equivalent behaviour.
Can a box section be used as a handrail post?
It may form part of a designed guarding system. Post size, base connection, rails and project actions must be reviewed together.
What should accompany an enquiry?
Send the member schedule, connection sketches, loads, restraints, exposure conditions and intended delivery format.
Detail the hollow section.
Build a clear assembly brief.
Share your member layout and joint requirements. Ask Vital to review the profile, connection and fabrication scope.