CATENARY · CONVEYOR FIELD GUIDANCE

Conveyor belt splicing basics: mechanical, hot and cold splices

Splicing · Technician

A splice is the weakest point of most belts. Choose the right type, get the geometry from the belt maker, and control preparation, cleanliness and curing — most splice failures in the literature are workmanship failures, not design failures.

Safety first: observe a running conveyor only from designated guarded positions. Isolate, lock out and verify zero energy, and secure take-up movement, before any hands-on check or correction.

1. Choose the splice type

Mechanical fasteners: fastest, used for repairs and lighter belts; check the fastener maker's rating and minimum pulley diameter against your pulleys. Hot vulcanised: highest strength and life, normal for main textile and all steel cord belts; needs a press, power and several hours. Cold (adhesive): textile belts where a press is impractical; sensitive to humidity, dust and cure time, and not for steel cord. For hot material, check the splice kit's temperature rating.

2. Geometry

Textile step splice: steps = plies − 1 (some makers use 2 steps on 2-ply belts); bias ≈ 0.3 × belt width (16.7°); splice length = step length × steps + bias. Step length depends on ply strength and comes from the belt maker. Steel cord: the number of stages and lengths depend on the ST rating and differ between makers by up to about 45 % — use your maker's splice diagram. Catenary's Splice geometry tab does the arithmetic.

3. Prepare safely

Isolate and lock out the conveyor, clamp the belt on both sides of the splice station, and secure the take-up or counterweight before releasing tension. Work in a shelter away from sun, rain and dust. Before cementing, check the dew point: the belt surface must be clearly warmer than the dew point (one instruction asks for at least 5 °C margin). Check splice-kit batch and expiry dates.

4. Mark, cut and buff

Mark from the belt centreline, not the edge, and square the reference line geometrically. Cut the bias and strip plies or cords without nicking the fabric or cord coating — knife damage is a leading failure cause. Buff lightly to a uniform texture; do not grind into the fabric. Keep prepared surfaces clean and do not touch them with bare hands.

5. Cement and build

Apply cement in the coats and drying times the kit maker specifies; never close a joint on wet cement or recoat cords once laid. Align the two centrelines, lay the tie gum, close the steps without trapped air, and finish the cover skives at about 45°.

6. Cure (hot splices)

Use edge irons about 1 mm thinner than the belt, release sheets on both sides and a thermocouple on every heating element. Count cure time only when all elements reach cure temperature, and follow the maker's time, temperature and pressure — makers differ widely. Cool under full pressure to the maker's release temperature (about 60–70 °C in most instructions) before opening; never open hot. For cold splices, respect the minimum waiting time before running.

7. Inspect and record

Check straightness, thickness match, edges, blisters, porosity and exposed plies or cords. Record date, splice type, kit batch, cure log, temperatures and the splicer, and add it to the conveyor record. Watch the first runs only from guarded positions; a splice that drifts once per revolution points to splice geometry.

Related Catenary calculators

Related standards on MechAtlas (status and edition)

Open this guide in the Catenary app ↗All field guides

Source note: Generic method synthesised from 14 splicing documents (SIG Rev.5 2018; ContiTech fabric splice manual 2015; REMA TIP TOP cold splice 07/2021; Mercurio REV.08/22; NILOS, Sempertrans V a/12.2020 and Dunlop v10.4 steel cord instructions; Eskom 240-120532564 Rev 3). Numbers for your belt must come from your belt maker.. Field guidance supports your judgment. Site procedures, manufacturer instructions and current standards govern final decisions.