Yaoniu galvanized sheet-metal ductwork

Pick the section and the joint together

The article describes seams, forming and a spring-clip flange arrangement. The catalogue lists integral and angle-steel flanges in separate columns. Ask for the drawing of the joint Yaoniu proposes, including gasket and reinforcement, so you know exactly what the price covers.

Round and rectangular ducts need different drawings and fittings. Pressure and acoustic behaviour also differ, so judge each route on its own data.

Leakage: set the class in your enquiry

Yaoniu's article calls its spiral construction leak-free but gives no test pressure, test method, sample or allowable leakage figure. Write the leakage class and test you need into the enquiry instead.

Ask Yaoniu to quote the run against your positive and negative pressure and the leakage acceptance. Seams, flanges, gaskets, sealant, reinforcement and supports all belong in that scope. Request a pressure and leakage test on a sample section as part of the order; the factory acceptance and pressure test guide sets out how to word it.

Ordinary ventilation and harder duties

The article names supply air, cooled air, kitchen exhaust, dust collection and conveying of bulk material as uses. It also separates humid or corrosive conditions from normal galvanized service.

For grease, condensate, dust, abrasive material or corrosive air, describe the medium, temperature and cleaning access. Then agree a matched construction and acceptance test with the designer and Yaoniu. Fire rating, corrosion allowance, abrasion life and cleaning method all need stating per order. If the run is insulated, ask for thickness, conductivity and vapour-barrier details of the delivered insulation; the insulation itself can be compared with products such as Heqiang PEF insulation.

What to send every bidder

One drawing-based requirement sent to all bidders keeps quotations comparable. Other fabricators listed here, such as Luhai spiral ducts, quote from the same kind of brief.

1. Describe the whole assembly

   Drawing revision, quantities, shape and sizes, sheet grade and coating, thickness schedule, fittings, flange or seam system, insulation and access doors.

2. State conditions and required tests

   Air or medium, flow, temperature, positive and negative pressure and the leakage and material acceptance. Ask the bidder to flag any duty outside its normal range before pricing.

3. Split the price

   Separate fabricated duct, flanges, seals, supports, packing, delivery and site installation. Ask for material and inspection records and the pressure and leakage results for the selected assembly.

Confirm these duct details with Yaoniu in writing

Before ordering, ask Yaoniu to confirm in writing: the gauge schedule for each size; the flange or seam system and gasket; the pressure class and leakage class the run will meet, with the test used; any fire, corrosion or noise rating you require; the insulation specification; the valid quality certificate; and price and shipment slot. The company itself, its sites and its differing output figures are covered on the Huzhou Yaoniu company page. Fix those items in the contract together with the approved drawings.