How to Properly Glue and Join EPDM Seals on Container Doors
Shipping containers form the backbone of global logistics and trade systems. A key element for keeping cargo dry, clean and safe is the door seal, which prevents water, dust, pests and extreme temperature fluctuations from entering. The quality of seal installation directly influences the service life of the container and the value of the transported cargo. The essential material is EPDM – a synthetic rubber with exceptional durability.
This guide is designed as a professional handbook of terms, technologies and correct procedures necessary for a high‑quality, safe and long‑lasting sealing of container doors. It is supplemented with current technical information from catalogs and manufacturers (Gumex, Rehm Dichtungen, GMS), including practical tips and tables.
Adhesive (Glue)
Definition:
An adhesive is a permanent glue intended for bonding EPDM seals to the metal frame of a container door.
Extended information and technical details:
- For gluing EPDM outdoors, highly resistant adhesives based on cyanoacrylate, polyurethane or special contact adhesives are required.
- Fast‑acting glue AR 925 is suitable for EPDM, working temperature –30 °C to +80 °C, very rapid cure, recommended to use a primer.
- Professional double‑sided tapes (Bonding Tapes BT/HT) are used for quick installation, absorbing vibrations and transport shocks.
- Cure time: For contact and polyurethane adhesives full cure is usually achieved in 24–72 hours.
- During gluing, surface cleaning and degreasing are essential (see “Surface Preparation”).
Practical tips:
- Apply a thin layer on one side, join the parts immediately, and press for a few seconds/minutes.
- When gluing outdoors always consider the recommended temperature range and humidity.
- Use a roller for even pressure along the entire length.
Activator (Primer)
Definition:
A chemical preparation that improves the adhesion of the glue to EPDM and metal surfaces.
Technical details:
- EPDM has low surface energy, so without a primer the joint is weaker.
- Primer based on organic solvents (e.g., isopropanol) is applied with a clean cloth or brush.
- “Flash‑off” time: 5–10 minutes; the surface must be dry/tacky, not wet.
- Without proper primer, premature joint failure may occur.
Practical tips:
- Work in a well‑ventilated area and wear protective equipment.
- Never apply primer to dirty or oily surfaces.
EPDM (Ethylene‑Propylene‑Diene Monomer)
Definition:
Synthetic rubber, ideal for manufacturing seals thanks to extreme resistance.
Technical details:
- Temperature resistance: –40 °C to +125 °C (some grades up to +150 °C).
- Excellent resistance to UV, ozone, weather, most chemicals, weak acids and bases.
- Long service life (decades) with minimal property change over time.
- EPDM profiles from reputable manufacturers (Semperit) have hardness 25–80 Shore A, typically 50–70 Shore.
- Not suitable for continuous contact with oils or gasoline products (use NBR instead).
Practical tips:
- Choose seals with declared European manufacture (Semperit) complying with REACH/ROHS.
- For extreme outdoor conditions always select a denser, fully vulcanized EPDM.
Extrusion (Extruded Seal)
Definition:
Manufacturing process: pressing heated EPDM through a die to create the final profile shape.
Technical details:
- Profile types: J, H, C, E (see table below). Standardized dimensions, custom production possible.
- A hollow profile improves compression and sealing.
- Lengths are usually supplied in 20 m, 25 m or 40 m rolls, or cut to size.
Practical tips:
- When replacing, always compare the old profile with the manufacturer’s catalog – small differences can affect sealing.
- Extruded seals are marked with a type (H, J…) and dimensions in mm.
Compression (Seal Compression)
Definition:
The amount the seal is compressed when the door is closed; critical for ensuring watertightness and airtightness.
Technical details:
- Recommended compression: 25–50 % of the original profile height.
- Insufficient compression = leakage; excessive compression = permanent deformation (compression set) and loss of elasticity.
- Measured with modeling putty or a gauge – see practical description in the introduction.
Practical tips:
- Never install an overly thick profile “just to be safe”.
- Measure the average gap at several points around the door.
Container Doors
Definition:
Double‑leaf doors at the end of a container, equipped with robust locks and seals.
Technical details:
- Made of CORTEN steel, standardized dimensions (door width 2 340 mm for 20 ft/40 ft containers).
- Each leaf has special grooves around the perimeter for the seal.
- The right door closes first; the left door overlaps and forms the main sealing line.
Practical tips:
- When replacing the seal, also inspect the frame for dents and straighten them.
- The locking mechanism must pull the doors tightly into the frame.
Container Seal (Door Seal)
Definition:
A profiled rubber strip (usually EPDM) that provides a watertight and airtight closure.
Profile types:
| Profile type | Usage description | Characteristics |
|---|---|---|
| J‑profile | Standard for most dry containers | Easy installation, high sealing |
| H‑profile | For refrigerated, special containers | Double sealing, higher sealing |
| C/E‑profile | Special applications, various manufacturers | Individual per container |
Technical details:
- Seal length: 7–9 m per leaf (depending on container size).
- Average service life: 10–20 years (depending on exposure and maintenance).
Practical tips:
- Regularly test sealing (light test from inside).
- Always replace the entire seal on one leaf, not just a section (exception: sectional repair).
Seal Gluing
Definition:
The process of physically fixing an EPDM profile to the door frame with suitable glue or tape.
Technical details and recommended procedure:
- Select glue/tape:
- For EPDM: fast‑acting glue (AR 925), polyurethane, contact adhesive, or double‑sided tape BT/HT.
- Prepare the surface:
- Clean and degrease (IPA‑water mixture, see below).
- Apply glue:
- Thin layer, press immediately, apply slight pressure along the whole length, optionally with a roller.
Practical tips:
- Perform gluing at temperatures above 10 °C.
- When using tape, peel the protective film gradually.
Miter Cut (Angled Cut)
Definition:
A cut at an angle (usually 45°) for joining in corners.
Technical details:
- Provides precise joining of two profiles in a corner and maximum sealing.
- Cut with a sharp knife or special scissors.
Practical tips:
- Start installation at one of the upper corners and work around the perimeter.
Mounting Strip (Fixing Strip)
Definition:
A metal (stainless steel/aluminum) strip for mechanically attaching the seal to the frame.
Technical details:
- Width: 10–20 mm, thickness 1–2 mm.
- Fastened with rivets or screws (see below).
- Often pre‑drilled to speed up installation.
Practical tips:
- Drill out old rivets with a drill of matching diameter.
- If the strip is corroded, always replace it with a new one.
Shipping Container
Definition:
A standardized transport unit made of CORTEN steel, sized 20′ or 40′.
Technical details:
- Construction: plywood or steel floor, CORTEN walls and doors.
- Types: dry van, reefer (refrigerated), open top, flat rack, double door.
- Each type has a specific seal profile and door sealing system.
Rivets
Definition:
Mechanical fasteners for permanently attaching the mounting strip.
Technical details:
- Types: blind rivets (pop rivets), material stainless steel/aluminum.
- Diameter: usually 4–5 mm, length according to door and strip thickness.
- Installed with hand‑operated or pneumatic rivet guns.
Practical tips:
- Drill out old rivets with maximum care to avoid damaging the door.
Seal Repair (Partial Replacement)
Definition:
Replacing only the damaged section of the seal, not the entire perimeter.
Technical details:
- Suitable only for localized damage (less than 20 % of the length).
- Join new and old profiles with joining tape or special glue.
Practical tips:
- After repair always perform a sealing test (light or water).
Surface Preparation
Definition:
Key step: removal of old seal, glue, rust and grease.
Technical details:
- Mechanical removal: scrapers, wire brushes, grinder.
- Cleaning: degreasing with isopropanol/water (1:1).
- Surface must be dry, dust‑free and free of grease.
Practical tips:
- After cleaning do not touch the surface with bare hands.
- Use disposable wipes/cloths.
Joining Tape (Seam Tape)
Definition:
Special, highly adhesive double‑sided tape based on non‑vulcanized rubber.
Technical details:
- Used for joining two pieces of seal (especially EPDM).
- Application: apply to surface with activator, after off‑gassing press the second piece, roll it down.
- Creates a permanently flexible, watertight joint.
Practical tips:
- Apply tape precisely on the edge, overlap about 5–10 mm.
- Overlapping tape increases reliability.
Seal Joining
Definition:
Process of permanently joining the two ends of an EPDM profile.
Technical details:
- Cold method: activator + joining tape or fast‑acting glue (with activator).
- Hot method (vulcanization): only in manufacturing, not suitable for field repairs.
- Cure time: depends on system (usually 20–60 minutes for glue, immediate for tape).
Practical tips:
- Align joints and press firmly.
- After joining let the joint rest for the recommended time.
“H” Type Seal
Definition:
EPDM profile with an “H” shaped cross‑section, used for increased sealing.
Technical details:
- Suitable for refrigerated containers and high‑traffic panel areas.
- Double sealing, higher compression, higher durability.
“J” Type Seal
Definition:
The most common profile for dry containers, easy to install and maintain.
Technical details:
- Profile with a hook for quick insertion into the groove.
- High sealing when compressed.
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