How to Clear Duct Blockage in FTTH Work?

Duct Blockage clearance point excavation

How to Clear Duct Blockage?

How to Clear Duct Blockage: We all know that duct clearance is necessary before fiber cable pulling or blowing. With the help of the DIT process, we found out the actual condition of the duct. Duct Blockage,kink,sharp bends in duct,leakage etc. all we can find out during the DIT process and duct blockage problem can be clear before cable pulling or cable blowing.

Sometimes we do the work of cable pulling or cable blowing in the existing duct. All caution is also required while working in the existing duct because any live cable can be available in adjacent existing duct. 

How to find out and Clear Duct Blockage

We will know from rodding whether the duct blockage. where is the actual point or how much distance is duct blockage from the MH/HH. We will measure the distance from the MH/HH and mark the duct blockage point. All work including excavation and reinstatement can be necessary to clear blockages in existing ducts prior cable pulling or cable blowing.

Any blockage found in existing duct must be confirmed by rodding both ways,once get the permission to clear a blockage is obtained if a double blockage situation in any one section exists, the second blockage must not be cleared until the first blockage is opened and the unproven section of duct between the blockages tested.

Should another blockage in the unproven section be identified,SIte engineer should be contacted to company authorities before a second dig is made to re-evaluate the situation.On completion the cleared duct section should be rodded and roped. After the clearance of duct blockage you have to install Blown Fiber Tubing into the cleared duct.

If additional bores in a multiway duct are found damaged in the same excavation they must be repaired but there is no requirement for these to be tested, rodded and roped.All rodding operations must be carried out with normal 25mm diameter rods, the use of smaller rods

i.e. continuous Cobra rods (approx. 12mm diameter) will be at the discretion of the work originator.

Duct Blockage Measurement Rule

The rate shall cover all repairs required at one location including the repair of additional bores in a multiway if they are found damaged in the same excavation.A location is limited to a distance of 3 linear metres between the beginning of the first and any subsequent repair kit and to one MH/HH to MH/HH length. Lead-time premiums are not applicable to this activity.

All blockages cleared should be recorded with the closing job pack with an accurate address,clear images of excavation point of duct blockage,GPS reading for each blockage including a center to center measurement.

Where a blockage cannot be repaired due to obstruction/damage caused by other plant the details should be entered on company cable route drawing, detailing position and clearances between plant with a description of what was found.

This information should be supplied to the work originator with photographs. Company authorities can issue the separate duct blockage clearance WO. If the company wishes to clear the duct blockage, it will fix a separate duct blockage clearance rate. Company can issue the includes all work, including excavation and reinstatement performed in an aborted attempt to clear a blockage in existing ducts.

Summary

It depends on the company's rule that which kind of work order to generate  to clear the duct blockage.What rate fixes for repair , what rate fixes for extra excavations. Mostly company cover all repairs required at one location including the repair of additional bores in a multiway if they are found damaged in the same excavation.Additional repairs, outside the 3 linear metres and all other repairs in the same section will be payable at the additional blockage rate and will be measured in a similar fashion.