Yardsticks in Tower Crane Operations

Tower cranes are versatile lifting equipment that have proven their utilities in lifting material for housing and real estate projects. Of late, the equipment have been making their mark in core construction jobs in the country. However, to derive the optimum utilization of the equipment, necessary precautions need to be taken during their erection, operation, and maintenance. Partha Pratim Basistha finds the details.

Tower cranes, like never before, have been making their mark in India's construction landscape. As construction job complexities gain further ground in the country, both in high end and real estate construction, enhanced recognition and acceptance of these steel structures is becoming an accepted norm among the construction fraternity. However, as population of these wonderful lifting equipment swell, requisite yardsticks are required to be adhered to by contractors for efficient and safe operation of tower cranes. This is essential to check escalation of equipment downtime.

Essentially characterized as a structure of steel, (Steel constitutes 80% of tower crane's components) the equipment require precautions both during erection and dismantling, most importantly during slewing operations. "Since equipment works in a static position lifting different load variants, foremost care has to be exercised during equipment's erection", says Mr. Ashwani Mattoo, National Sales Manager, M a n i t o w o c Cranes and Potain Tower Cranes, India. According to Mr. Mattoo, "it is quite essential that soil is tested to identify ground bearing strength at the site of erection. This in turn will provide stable foundation for crane to be erected."

He adds, "with appropriate foundation in place, it is important that foundation is uniformly leveled. This will prevent crane from collapsing during lifting of higher loads. Dually, right foundation will check any anomalies in alignment of crane during its positioning and operation." Significant would be to firmly place four corners of mast section over foundation.

Similar views are expressed by Mr. V.N. Deshpande, Vice President-Business Development, Spartan Engineering Industries Pvt. Ltd.

Main erection has to be carefully followed by approp-riate joining of mast sections. According to Mr. Nilesh Savant, Service Engineer, Tower Crane, Liebherr India Pvt. Ltd., "while jointing nuts and bolts of mast section, torque has to be given as per prescribed specifications. It is vital to see the capacity of bolts."

Second vital stage of erection is identifying right anchorage point to pillars of construction. This ideally has to be done when crane has to be extended above its free standing height. Identification of correct anchorage point needs to be done through calculations and the calculations have to be done considering height and pillar that could be ideal for anchorage. Selection of appropriate anchorage is important so that crane jib can cover a good part of construction site at a given height. Furthermore, anchoring support has to be quite strong.

Vital: Area Feasibility

Nonetheless, the most significant part to be preceded before erection and commissioning of tower cranes, would be a thorough study involving feasibility of the area where tower crane has to erected and perform. While soil testing and zero level foundation are of value. It comes under the ambit of feasible study. Other domain of study would be whether job site has got comfortable space to assemble and dismantle cranes. Road access to site has to be seen, if not available then it needs to be constructed. This is because erection and dismantling of tower cranes are supported by the aid of mobile cranes that has to be transported to the job site or its near vicinity by self or through a separate vehicular transportation arrangement. Having a well connected site access for supporting cranes would also help in any condition to have economies of scale for construction project.

Availability of adequate space is also important. This is because, mobile cranes involved in assembling would, in obvious sense, be randomly lifting mast sections and assembling those at different heights through its boom at different extensions. Care has to be taken about the close proximity of buildings or any other construction projects at assembly site because mobile crane boom has to undertake slewing.

Presence of building's proximity to construction job site is also vital. This is so as to prevent jib of tower cranes from colliding with the same during slewing. In case of presence of other buildings or close proximity to other construction projects, at the same job site, it would be necessary to place jib at great heights to support safe slewing of tower cranes. Right working space availability is also very significant for smooth internal and external working of tower cranes. But above all, it would once again lead to smooth erection and dismantling of crane without any obstruction.

Placing equipment in right position by making height adjustments is essential to prevent crane counterweight being obstructed during slewing. Moreover, right equipment positioning through placing jib of crane 2-3 meters away, as per conventional standard, can also prevent jib collisions. This is where multiple tower cranes are functioning at same job site. Collision can be prevented by deploying tower cranes having luffing jib arrangement etc.

However, element of outmost value, as most tower crane equipment manufacturers and distributors agree would be, selection of a right, skillful and fearless operator. This is because he has to perform at critical heights. This is precisely in high end projects.

Maintaining Safety Standards

Operation has to be closely guided by adhering to right safety standards. One of the most important of these safety standards is the wind velocity in project vicinity. According to Mr. S. K Malvi, Director Technical, Anupam Industries Limited, "it is much essential for the contractor to evaluate the wind velocity before erecting the tower crane at the job site. This is essential as pressure due to high wind speed may lead the tower crane to derail or collapse." As per Mr. Malvi, "as a part of service support for erection of the tower crane we provide due advice to the contractor in evaluating the wind speed during erection and operation of the tower crane." Anupam Industries manufactures tower cranes bearing a capacity of 5 tons and 6 tons in technical collaboration with Alfa SRL of Italy. The cranes are available with top‎less features and cathead features.

Wind pressure in tower cranes is determined with anemometers where a crane operator can read wind velocity. Cranes are safe to operate in wind velocities of up to 40 kmph. Program Logic Control Devices assist in automatically shutting down crane when wind velocity is exceeded.

Additionally, proper maintenance of rail track on which tower crane is working in infrastructure projects has to be ensured. It is important to use proper rails for movement of the tower cranes. Rails should be absolutely parallel and well bedded down on a solid base. Tracks should be earthed. It should be straight to prevent derailment of tower cranes at job site. However, construction companies opine that there has to be safety regulation in place which should be effectively implemented, all which would lead to hazard free use of tower cranes in infrastructure projects. Significantly, overloading should not be allowed under any circumstances as majority of accidents in tower crane occur due to lack of information on loading or intentional overloading. Besides, uninterrupted power supply has to be ensured to crane for its consistent performance. Further, plumb line has to be perpendicular as slightest deviation from the same would render the working output inaccurate.

Customer Support Galore

Responding to requirement for smooth erection, commissioning and dismantling of tower cranes equipment manufacturers and distributors in India are offering an array of services to contractors. According to Mr. Ashwani Mattoo, "For our tower cranes, Manitowoc Crane Care, provides Manitowoc's comprehensive support program. This includes Expert Field Service, Prompt Parts Availability, Technical Support, Classroom, On site Training Program, and so on."

He adds, "most of service engineers of Manitowoc Crane Care are well experienced and trained to work on tower cranes to perform jobs like erection, maintenance, operation and troubleshooting with proper safety procedures. Additionally, we have got a training department which keeps evaluating training requirements of technicians and providing necessary training for them to upgrade their knowledge and skills. Further, we also offer training to customer's technical staff so that they can understand basic functioning of Cranes and can rectify smaller problems themselves to increase productivity and reduce downtime."

Manitowoc Crane Care has offered services to cranes working in hydro Power projects, cement plants, cooling towers, Bridges in India (such as the Bombay – Worli Sea Link Project), and construction of highrise buildings. Manitowoc Crane Care has three service stations in north, west and South India to provide customer service promptly.

Escorts Construction Equipment Ltd. also offers comprehensive customer services. According to Mr. Sheetal Malik, DGM Sales, Escorts Construction Equipment Ltd. (ECEL), "we have a dedicated core team to support erection and commissioning of tower cranes in India. The Core team with highly experienced associates in tower cranes provide training to dealers for smooth erection, commissioning of tower cranes. Further, Core team also provides direct training to customers as per requirement. Service support is complemented through component availability through our pan-India dealership network." ECEL distributes Chinese manufactured Wei-Huata tower cranes in India.

Adequate customer support is offered by Liebherr India Pvt. Ltd. According to Mr. Pulok Gupta, Managing Director and Head of Sales, Liebherr India "our service support is benchmarked on prompt availability of service engineers within 24 hours of customer call. This ensures 99% of crane availability. Apart from providing on field service, our service engineers are competent enough to guide customers to undertake trouble shooting operation of cranes over phone itself."

He informs, "to provide component and spares availability at right time, we follow a concept of "networking of service" i.e. we keep pooled some amount of critical components with our customers. Based on the demand, we source and transfer required components from one customer to other. Followed by equipment off take, we replenish component stock from sourcing customer from our mother warehouse in Navi Mumbai. This practice is followed in chains between our customer network."

Well trained service engineer support is provided by ABG Cranes. According to Mr. R.B. Pandey, General Manager, Marketing, ABG Cranes Ltd, "customer support is key to us. We have well trained team of 20 service engineers to provide complete technical guidance from erection, to commissioning and dismantling of tower cranes. The engineers are available at a call of 24 hours." Mr. Pandey states, "Service engineers would be enhanced with population of tower cranes rising in near future. ABG Cranes market Chinese manufactured Yangmao cranes in India.

Well placed service backup is also vital says Spartan Engineering. According to Mr. Deshpande, Vice- President Business Development, "we provide end to end service for tower cranes being supplied by us. While supplying a tower crane, we undertake a total contract, from providing technical support to erection, commissioning and dismantling, preceded by site inspections by our service engineers. This provides us an edge over our competitors. Besides, we are well placed in offering thorough component support to our customers." Spartan distributes GJJ and SQCL Chinese manufactured tower cranes in India."

Though service back up are available for operation and maintenance of tower cranes in the country. There has to be a sustained information exchange between manufacturers and users of tower cranes. It would be more beneficial if the operators use their own discretion for safe usage of cranes. This will lead to usage of tower cranes in construction projects across the value chain. Not to mention their increased usage for the time to come.