履带起重机操作手册

3.7 Underground cables

With special equipment, the crane can also be used for underground working.

3.7.1 In underground working, it is possible to damage: a) Underground electric cables b) Gas pipes c) Telephone, TV, and data cables d) Sewage pipes, district heating supply pipes, etc.

Warning

(1) If a live underground cable is damaged, lives are at risk from electric shock.

(2) There is an extreme danger of explosion and fire in the vicinity of a damaged gas pipe.

Measures to be taken during operational planning:

The construction company doing the work is responsible for gathering accurate information about possible underground cables within the working area of the equipment so that work can be done safely: a) Obtain relevant information from the relevant utility companies. b) Examine the "as completed" plans of:

1) Utility companies (electricity, gas and water)

2) Cable users (telecom companies, factories, transport companies) c) Only use the latest and effective plans. d) If there are any deviations or extensions to a project, initiate new inquiries. e) If in doubt, localize the underground cables around the site using a locating device. f) The relevant utility companies, cable users and public authorities:

3) Building authorities.

– Must be informed in good time about the start of the work g) When several construction companies are involved, their activities must be coordinated. All companies must have the same up-to-date information on underground pipes, etc. on the construction site.

– Must be asked for written approval for the civil engineering work to be done.

3.7.2 Safety precautions and protective measures when operating the equipment near underground cables

a) Do not start work until you have obtained all the approvals from the utility companies and the cable users b) The equipment operator must obtain all relevant information about the exact location of all underground cables before starting work. These plans must be readily accessible at the construction site.

Operator’s Manual for Crawler Crane

Operator’s Manual for Crawler Crane

履带起重机操作手册

c) Operate the equipment with particular care near underground cables, all applicable local safety guidelines as well as the special guidelines and safety measures of the utility companies must be noted and obeyed.

d) In the event of any unexpected encounters with underground cables or associated warning sign and protective coverings, cease working with the equipment immediately and inform the appropriate superiors.

e) It is prohibited to uncover underground cables with the equipment The underground cables must only be uncovered manually with blunt tools f) Secure, support, or prop up all exposed underground cables so that they cannot sway, slide, or become deformed. g) Stabilize the cable ducts and trenches and secure the edges to prevent caving.

3.7.3 Notes in connection with gas pipes

a) Whenever the position of the gas pipe casing changes or the casing is damaged, report this to the appropriate gas company. The gas pipe can only be backfilled after inspection, repair, and approval by specialist personnel from the gas company.

b) All devices of the gas supply network around the site must remain accessible (fittings, valve boxes, manhole covers, etc.). Existing markings and information signs must not be covered, rearranged or removed.

3.7.4 The consequences of a gas pipe’s damage

The escaping gas: a) Forms an inflammable gas-air mixture around the affected area. b) Can strike personnel or equipment if it is under high pressure. c) Not only endangers personnel and equipment on the site, but also passers-by and residents in the neighborhood.

A gas fire can develop in seconds and spread explosively. In a conventional supply pipe with a leak of 2" (50 mm), for example, the flames can be up to 10 m (33 ft) high if the gas is escaping at a pressure of 1 bar (14.5 psi). The equipment and surrounding construction equipment will be burned quickly

Even a minor change in the position of the gas pipe can result in damage to other sensitive points of the gas network, for example connection points or house feeder pipes. Leaks and small leaks that are not immediately detectable are very dangerous if gas is allowed to escape over a lengthy period of time and penetrate along the gas pipe network into the surrounding buildings. An explosive gas-air mixture is formed considerably quicker in enclosed areas than in the open air. Every source of ignition, such as On /Off switches on electrical equipment or the turning on of a light, can trigger an explosion.

Corrosion can cause leaks to form within 5 -10 years with minor damage to the casings of metal gas pipes.