Water-Blocking Tapes
Longitudinal water blocking for power and communications cables
Water-Blocking Tapes
Water-blocking tapes (CDZD) consist of a non-woven polyester backing impregnated with superabsorbent polyacrylate powder. On contact with moisture, the polyacrylate swells quickly to form a gel that blocks longitudinal water progress inside the cable, limiting damage to the entry area and easing fault location and repair.
The protection mechanism is passive until water ingress occurs: the tape stays dry and flexible during normal cable operation and is activated only when moisture is detected. This distinguishes swellable tapes from metallic barriers, which provide permanent tightness but cannot contain penetration once it has occurred.
Thickness selection depends on the space available between cable components and on the volume of water expected to be managed in case of failure. Thicker references offer greater absorption capacity and swelling speed, while thinner ones adapt to compact constructions where space is limited.
How to choose the right one?
The right reference depends on the balance between required blocking capacity, available space and mechanical strength during manufacturing. Swelling speed indicates the response rate to the presence of water.
| Reference | Thickness | Grammage | Tensile strength | Swell 1 min | Swell 3 min | When to choose |
|---|---|---|---|---|---|---|
| CDZD-10 | 0.10 ±0.01 mm | 40 ±5 g/m² | ≥20 N/cm | ≥3 mm | ≥4 mm | Very tight spaces, compact constructions |
| CDZD-15 | 0.15 ±0.03 mm | 60 ±5 g/m² | ≥25 N/cm | ≥5 mm | ≥8 mm | Communication cables, limited spaces |
| CDZD-18 | 0.28 ±0.03 mm | 65 ±15 g/m² | ≥30 N/cm | ≥6 mm | ≥9 mm | Capacity/space balance |
| CDZD-20 | 0.20 ±0.03 mm | 70 ±10 g/m² | ≥30 N/cm | ≥10 mm | ≥12 mm | LV/MV power cables |
| CDZD-25 | 0.25 ±0.03 mm | 80 ±10 g/m² | ≥35 N/cm | ≥10 mm | ≥14 mm | High absorption capacity |
| CDZD-30 | 0.30 ±0.03 mm | 90 ±10 g/m² | ≥35 N/cm | ≥12 mm | ≥16 mm | Maximum protection, HV cables |
Technical specifications
The values shown below come from tests run to international standards and characterise the material's behaviour both during processing and in service.
Thin-thickness references (CDZD-10 to CDZD-18)
| Property | Test method | CDZD-10 | CDZD-15 | CDZD-18 |
|---|---|---|---|---|
| Thickness (mm) | ISO 9073-2 | 0.10 ±0.01 | 0.15 ±0.03 | 0.28 ±0.03 |
| Grammage (g/m²) | ISO 9073-1 | 40 ±5 | 60 ±5 | 65 ±15 |
| Tensile strength (N/cm, min.) | ISO 9073-3 | ≥20 | ≥25 | ≥30 |
| Elongation (%, min.) | ISO 9073-3 | ≥12 | ≥12 | ≥12 |
| Swell rate 1 min (mm) | GB 450 | ≥3 | ≥5 | ≥6 |
| Swell rate 3 min (mm) | GB 450 | ≥4 | ≥8 | ≥9 |
Medium/high-thickness references (CDZD-20 to CDZD-30)
| Property | Test method | CDZD-20 | CDZD-25 | CDZD-30 |
|---|---|---|---|---|
| Thickness (mm) | ISO 9073-2 | 0.20 ±0.03 | 0.25 ±0.03 | 0.30 ±0.03 |
| Grammage (g/m²) | ISO 9073-1 | 70 ±10 | 80 ±10 | 90 ±10 |
| Tensile strength (N/cm, min.) | ISO 9073-3 | ≥30 | ≥35 | ≥35 |
| Elongation (%, min.) | ISO 9073-3 | ≥12 | ≥12 | ≥12 |
| Swell rate 1 min (mm) | GB 450 | ≥10 | ≥10 | ≥12 |
| Swell rate 3 min (mm) | GB 450 | ≥12 | ≥14 | ≥16 |
Thermal and environmental properties
| Property | Test method | Value |
|---|---|---|
| Short-term thermal stability | Q/TR.J02.031-2000 | 230°C |
| Long-term thermal stability | IEC 216 | 90°C |
| Moisture content | ISO 287 | ≤8% |
Construction
| Component | Material |
|---|---|
| Backing | Non-woven polyester |
| Active agent | Superabsorbent polyacrylate powder |
| Type | Single-side, non-conductive |
Values shown are typical and do not constitute binding specifications.
Available variants
Tape type
- Single-side non-conductive (CDZD) — standard
- Semiconductive (WBSC2S) — for HV cables with partial-discharge control
Swelling-agent application
- One side — standard
- Special configurations on request
Delivery formats
The supply format directly influences process continuity and taping efficiency. Material can be supplied in different formats and dimensions adapted to each machine type and production speed.
Pad / Roll (pancake)
Pancake format
Spool (TWS / STS reel)
Automatic reel
Other formats and dimensions available on request. Custom slitting service available.
Application sectors
Need technical advice?
Our technical team is available to help you select the optimum material for your application.
Custom slitting
Up to 1200 mm width, ±0.50 mm tolerance
View service
Spooling
Pad to TWS/STS spool conversion
View serviceWe process material from our stock or material supplied by the customer.
Need
technical advice?
Our technical team is available to help you select the optimal material for your application.