How to Read a Purlin Section Drawing for an RFQ

A purlin inquiry is easier to review when the cross-section dimensions and member length are clearly separated. The current VANTRO RFQ accepts section height H, flange widths B1 and B2, lip dimensions C1 and C2, material thickness t, and member length L. These values belong to each material item independently, so different C and Z purlins can be listed in the same inquiry without combining their dimensions.

This guide explains how to report dimensions from an existing section drawing. It does not select a section, calculate load capacity or provide structural design advice. Use project drawings or requirements confirmed by the responsible project team.

Purlin RFQ checklist

For each purlin item, provide what is available:

  • section type: C Purlin or Z Purlin;
  • section drawing or marked sketch;
  • section height H in millimeters;
  • flange widths B1 and B2 in millimeters;
  • lip dimensions C1 and C2 in millimeters;
  • material thickness t in millimeters;
  • member length L in millimeters;
  • material grade, only when confirmed;
  • finish, only when confirmed;
  • hole positions or other hole requirements;
  • quantity and unit, or “Not decided”;
  • destination and drawing availability;
  • additional project or document requirements.

Every dimension is optional in the RFQ. Do not estimate a value merely to complete the form.

How to use the existing C and Z section illustrations

Use only the verified C-section or Z-section illustration shown in the current VANTRO Multi-Material RFQ. The selected material category determines which illustration is shown. The diagram is labelled “Illustration only — not to scale.” It maps the cross-section labels for an inquiry; it does not define the final shape or select a structural section.

H — section height

H identifies the overall section height shown on the cross-section illustration. Enter the value from the drawing in millimeters. If the drawing uses another naming convention, provide the drawing or describe the correspondence in the notes.

B1 and B2 — flange widths

B1 and B2 record the two flange widths separately. The fields allow unequal values. Do not enter one value for both unless the drawing confirms that they are the same.

C1 and C2 — lip dimensions

C1 and C2 record the two lip dimensions separately. The fields allow unequal values. If one or both dimensions are not shown, leave the relevant field blank and provide the drawing for review.

t — material thickness

t is the material thickness from the confirmed drawing or purchasing specification. Enter it in millimeters. Do not select thickness from an unrelated product, infer it from a photograph or use this guide to determine a structural requirement.

L — member length

L is not part of the cross-section diagram. It records the required length along the purlin member and must be stated separately from H, B1, B2, C1, C2 and t. If a project needs several member lengths, create separate material items or identify each length and quantity clearly.

Section type

Choose the category that matches the confirmed drawing: C Purlins or Z Purlins. This guide does not determine which section is structurally suitable for a project.

Grade, finish and holes

The current RFQ leaves Grade and Finish as optional buyer-entered fields. Use the exact wording from the project documents. Use the optional hole-requirements field to describe known hole positions, patterns or drawing references. This guide does not establish a standard grade, finish or hole layout.

Quantity and destination

Select “Enter quantity” only when a quantity is available; otherwise select “Not decided.” Provide the destination country and drawing or material-list availability. These details help organize the RFQ but do not create an availability or delivery promise.

If you do not know all the dimensions

Submit the drawing, sketch or project schedule available and leave uncertain dimensions blank. You can also select “Not sure” where that option is provided. The RFQ permits submission without completed cross-section dimensions. The team can review the supplied information and discuss the closest available specification, but final selection and structural suitability must follow the project’s confirmed engineering requirements.

Related product and capability information

Send a purlin drawing or known dimensions

Open the Request a Quote form, choose C Purlins or Z Purlins, and enter any confirmed H, B1, B2, C1, C2, t and L values. Leave unknown fields blank for review.

Buyer questions

Why are B1 and B2 separate fields?

The RFQ permits the two flange widths to be entered independently because the supplied drawing may show unequal values. Enter only what the drawing confirms.

Are t and L both cross-section dimensions?

No. t records material thickness. L records the required member length and is explained separately because it is not shown on the cross-section diagram.

Can I submit an inquiry without all seven values?

Yes. The dimension fields are optional. Include the drawing or notes available and leave unknown values blank.

Does this guide tell me whether to use a C or Z section?

No. It helps communicate an existing requirement. Section selection and structural performance must be confirmed through the project’s engineering and design process.

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