Chiming the changes

Have you passed through East London recently and thought you saw a giant wind chime hanging in the sky? Well you weren't imagining it. For among the buildings springing up in the Canary Wharf development is one that is challenging the way that mechanical services are designed and installed in tall buildings. These 'wind chimes' were part of a new method of installing the pipes that has been so successful that it is set for widespread use elsewhere.

Externally, 10 Upper Bank Street could be any number of office blocks under construction in London's Docklands. It is a speculative design that conforms with the surrounding glass clad buildings and has three distinct sections: a 38-storey tower, a five-storey unit dubbed the podium and an atrium linking the two.

As is standard on Canary Wharf projects, the m&e services contracts for the building were tendered for in packages. Haden Young won the contract for the shell and core mechanical and plumbing services in July 2001 and was on site within two weeks. The structural design was complete at this stage and the basic design of the services routes in place. It was in the development and co-ordination of this design that the new techniques began to take shape. Haden Young undertook this process in liaison with m&e consultant H H Angus.

There are several plantrooms throughout the building. The main one is at basement level; from here two main risers feed through the tower core, with services branching off to small plantrooms on each floor that will hold local air handling units. A downward feed to the upper floors is supplied by two roof level plantrooms and a further plantroom on floor five holds ahus.

The podium is fed by two risers and has a separate plantroom on its roof – the design of which allows the building to be extended in future if needed.

Installation innovation
With similar buildings all around, why the need for a new installation system?

"We wanted to try to mitigate the number of welds and the handling in the risers, as it's probably one of the most difficult areas of installation," explains Richard Rowledge, senior project manager with Haden Young.

The idea was to install longer lengths of pipe, hence reducing the joins. The simplest way to install these increased lengths, the team established, was to drop them from above, rather than as standard through the limited space available at the base. This required careful planning and close co-ordination with the other construction team members, in particular the steel contractors.

One of the main issues was crane time. "We could only do this at certain times because the crane was in great demand," explains Rowledge. With four mains water pipes to be installed in each riser, installing each piece separately could potentially cause delays to building work. This led to the development of a system where several lengths of pipe could be installed at once. On closer examination, the two risers are slightly different: one is split with structural steel, with two pipes either side; the second riser allows the four pipes to be fitted in a straight line.

At each floor, a steel frame with a right-angled lip was fitted around the hole in the slab for the risers. Specially pre-fabricated steel plates were then loosely laid on these frames. The plates were slightly smaller than the opening to allow for building tolerances and had two or four lipped holes of equal diameter depending on the riser.

"We devised a rsj lifting beam with lugs and hung 12·6 m-long lengths of pipe on this," explains Rowledge. The pipes were specially manufactured by British Steel with short lengths of steel welded to the outside of one end that had a hole ready bored to take the hanging wire. The opposite end of the pipe was chamfered ready for welding and to ease the process of fitting them together. This minimised the work to be carried out on site to enable this plan to work.

  The 12·6 m length was chosen to suit the floor height in the building: it is 4·2 m between floor slabs, so each pipe length completed the installation on three floors. It also meant that all welding could be carried out at a height of 900 mm – improving health and safety and working conditions on site.

The pipes were shackled to the beam lugs and lowered into the building. The team trialled the process by using two pipes, but quickly progressed to installing four at a time. With the steel plates loose in the risers, a team was ready to adjust their position and guide the pipes through to the floor below, where this process would be repeated. The centre pipes were lowered 100 mm before the outer ones so that only two had to be handled at once. When the pipes were in place the steel plates were welded into position and the gap between the pipe and plate sleeve filled before the concrete was poured to complete fire-sealing of the risers.

The installation was carried out as the building progressed, with the construction team working around 8-9 floors in advance of the contractors. It took four days to cast a floor; the pipes were being installed at a rate of 208 m/day.

Use of this method has brought a positive response. Rowledge explains: "Canary Wharf liked it so much they are now designing other buildings around the system." This means arranging the steel so that all pipes can be installed in a single drop, something not possible here as the structural design was complete before Haden Young was appointed.

Another unusual feature of the building is the expansion system. The client specified that no expansion joints be used in the mechanical pipework as they considered it a weakness. "Chilled water is not too much of a problem because it is in contraction and the building is operating 24 h a day, so once it's in operating condition it's not going to vary much," explains Rowledge. However some pre-construction expansion of the pipework is inevitable so another method had to be found to overcome the initial settling movement.

This has been solved by using a series of springs and brackets. When the pipes exit the top of the building they pass through a series of goalpost supports, from which they are hung by support bracketry attached to compressed springs. "As the pipework expands, the springs decompress and some of the load comes off the pipework and is transmitted into the riser," explains Rowledge. The springs can take up to six inches of movement and gradually decrease in size as the distance from the roof opening increases and the pipe movement lessens.

Joined-up thinking
The shell and core electrical services were carried out under a separate contract by Phoenix Electrical.

Again there are two electrical risers in the main tower, feeding the east and west sides separately, and two satellite risers in the podium. The supply is by rising and falling mains, dividing at level 17. The main switchroom is at basement level one. Here two incoming supplies feed two mv switchboards and four double-ended packaged substations. There are two further packaged substations in the rooftop plantroom. Distribution is by busbar and back-up power is by standby generators under another package.

Haden Young and Phoenix worked in close co-ordination throughout the installations. The two firms had weekly meetings and shared an office on site, easing communications. This was further helped by use of the Bovis Hummingbird electronic communications system, on which the construction drawings were held so team members could access all drawings to simplify co-ordination. Both firms have won contracts for fit-out packages on the building following their initial work. This fit-out is now well underway, with Clifford Chance set to move in late summer.