CW-5 and CW-8 Grades of Non Woven Water Blocking Tape

Check the electrical duty before choosing CW-5 or CW-8. A purchase request for “0.30 mm non woven water blocking tape” can produce two plausible quotations for different materials. Chaowang lists a 0.30 mm grade in its CW-5 family and a grade of the same nominal thickness in its CW-8 family. Before choosing either, ask the cable designer one question: does this layer also have to carry out a semi-conductive function?

Where will the non woven water blocking tape sit?

Ask for a cropped drawing that shows the tape and the layers on either side of it. On a screened power cable, “near the copper screen” leaves at least two possible positions. Mark whether the tape touches the insulation screen, sits over the screen wires, or appears in both places. Give each position its own item number so that a purchasing substitution for one layer does not silently change the other.

The distinction appears in a real cable design. In its guide to BS 7870-4.10 cable, Prysmian UK specifies semi-conducting tape where tape is fitted beneath the copper wire screen. In its water-blocked designs, tape can sit above the wires or on both sides of them. That example explains why location matters. For a different cable, the designer should identify the electrical duty on its own drawing and sign off on the material offered for that position.

If the drawing shows the location but says nothing about electrical behavior, send the designer a marked copy with space for a short answer. Ask whether the layer needs a specified electrical resistance, whether it must meet an insulating requirement, or whether the design sets only a water-blocking requirement there. Purchasing can use that answer to compare quotations on the same basis.

What does a 0.30 mm quotation actually cover?

The CW-5 single- and double-sided grade table lists polyester nonwoven fabric, superabsorbent resin and adhesive. There are two separate 0.30 mm entries within that family. ZDD30 appears in the single-sided group and ZDS30 in the double-sided group. If this is the layer your drawing calls for, put the grade code and side configuration on the sample request. For a single-sided grade, ask which face should contact the intended water path when the roll is mounted.

For a layer with a specified semi-conductive duty, consult the CW-8 semi-conductive water blocking tape specification. Its BZSD30 entry lists a thickness of 0.30 ± 0.03 mm, and the family uses a semi-conductive adhesive. Ask for the offered grade's electrical test report and the acceptance limit for this cable. Identify the property by name and unit. Surface resistance and volume resistivity describe different measurements and cannot be compared as bare numbers.

On the quotation comparison sheet, keep one row per offered grade. Include the layer item number, side configuration, nominal thickness and tolerance, electrical requirement where applicable, and supplier document revision. This also helps with a later reorder. A stock description such as “black swelling tape” or “white 0.30 tape” gives a warehouse clerk too little information to pick a qualified roll.

What should be checked on the sample and on the cable?

At sample receipt, record the grade, lot and roll number before cutting specimens. Read expansion rate and expansion height as separate properties. The CW-5 table expresses the first in millimeters per minute and reports the second at three minutes. Ask which liquid, temperature, fixture and starting point the supplier used. Keep those conditions beside the value if a second supplier has used a different method.

On the production trial, record where the operator fitted the tape, how it fed from the roll and whether the edges maintained the intended coverage. When the trial includes a semi-conductive layer, retain the electrical result for the material and carry out the checks the cable design requires. To qualify longitudinal water blocking, use the finished-cable test named by the customer. Record the entry point, observation point and acceptance rule along with the reel identity so the result can be traced back to the actual build.

Binding may appear on the same drawing under a different item number. A buyer reviewing the Chaowang nonwoven cable tape range can request CW-1 for a core-binding layer separately. Keep that item on its own purchase line so the supplier can quote the width and roll format required at the binding head.

Questions to settle before issuing the order

Can purchasing quote both families while the drawing is under review? Yes. Ask for separately identified options, with the electrical and water-blocking evidence for each. Leave material approval open until the designer confirms the duty of that layer.

Does double-sided mean semi-conductive? Double-sided identifies a construction option in the CW-5 table. A project requiring a semi-conductive function needs a grade whose electrical properties are documented for that duty.

What if a supplier offers a different tape thickness? Have engineering review the proposed tolerance and available space in the wrapped build. Note the approved change against the drawing revision before authorizing the substitute.

What does the sample label need to say? Include the exact grade, slit width, roll identity and lot. Mark the active face or unwind direction if the design depends on it.

What should accompany a repeat order? Quote the approved grade and data sheet revision, the cable layer item number and the sample approval reference. That gives the supplier a clear basis for flagging a change.

For a non woven water blocking tape quotation, send the marked layer drawing, electrical requirement, slit width and specified water test to Jiangsu Chaowang New Material. Ask for the exact CW-5 grade and a trial roll, or identify the semi-conductive duty so that the CW-8 option can be reviewed against the same drawing.

Technical References

• Non-Woven Water Blocking Tape for Cable, CW-5 — Jiangsu Chaowang New Material. Gives the single- and double-sided grade codes, nominal thicknesses and swelling properties.
• Semi-Conductive Water Blocking Tape, CW-8 — Jiangsu Chaowang New Material. Identifies the semi-conductive adhesive and the dimensions of BZSD30.
• Product Guide, BS 7870-4.10 — Prysmian UK, June 2024. Describes tape placement and the electrical duty beneath the copper wire screen for the cable construction illustrated.