Masonry Magazine December 1982 Page. 19
Tilechem is a masonry contractor specializing in the construction of tanks and vessels used in the pulp and paper industry. These tanks and vessels must be acid resistant. Some of the tanks and vessels constructed by Tilechem are fairly small "chests", many of which are located within existing buildings. However, the company is also engaged in the construction of large outdoor circular tanks which may be over 100 feet high. These tanks are generally constructed of an exterior wall of insulating block and an interior wall of acid resistant tile. Between the two walls is installed reinforcing rods. Concrete is then poured into the cavity. To avoid undue pressure on the walls of the tank, generally only about 12 to 16 inches of concrete will be poured in any one day. This fact means that each tank will be constructed at a rather slow pace and over a relatively long period of time.
On straight-wall tanks, the regular construction crew will consist of one or more masons and a number of mason tenders belonging to the Labourers' union. The masons lay both the blocks and the tiles. The mason tenders transport the block and tile to the masons, mix the mortar and transport it to the masons, prepare the concrete, operate a concrete pump, man the hose from the concrete pump and also perform any other labouring type work. The general practice has also been for the mason tenders to transport the scaffolding frames and put them into place in concentric rings both inside and outside of the tank as it is being constructed. The scaffolding is erected just slightly ahead of the blocks and tiles. When the tank is completed, the mason tenders dismantle the scaffolding. As the tank is being built, a crew of reinforcing rodmen will come in at intervals to install the reinforcing rods. On any one tank the rodmen might be on the site about six separate times. The rodmen work off the already erected scaffolding. On straight-wall tanks carpenters will usually be called in for the first time to build and install wooden forms for a concrete roof. Sometimes forms must also be built for haunches located near the top of the tank. In installing the forms the carpenters work off the already erected scaffolding. Further, the inner ring of scaffolding is generally used to support the wooden forms for the roof.
Most large tanks constructed by Tilechem and its competitors in Northern Ontario are of the straight-wall type referred to above. The instant complaint, however, arose primarily out of the construction of what is referred to as a high-density or "neck-down" tank. These tanks have a shape similar to that of an upside down milk bottle. Stock material is put into these tanks at the top at a high consistency. In the bottom or "neck" of the tank the stock is diluted and mixed with an agitator before it is used. Because of its peculiar features, a high-density tank may be able to hold the equivalent of three times the amount of stock stored in a similar size straight-wall tank.
Because of the shape of a high-density tank, there is a greater need for carpentry work in its construction. Trusses must be constructed and installed and then plywood placed over them to create a form for the "flareout" between the narrow "neck" of the tank and the wider upper part. This is in addition to any form work associated with the roof and any haunches. Additional scaffolding is also required on a high-density tank. On a straight-sided tank there is generally one outer ring of scaffolding, one inner ring, and apparently often a centre tower of heavy scaffolding used to support a lift. On the exterior of a high-density tank, however, there is generally a short ring of scaffolding used to allow work to progress on the neck portion, and a second ring from the ground to the top to allow work to be done on the major straight-wall part of the tank above the flareout portion. On occasion, a third outer ring of scaffolding is also used. Inside a high-density tank there is a short ring of scaffolding around the bottom, as well as a second ring from the top of the flareout to the top of the tank. This second ring rests on beams at the top of the flareout normally installed by carpenters. Generally, there will also be a centre tower of heavy-duty scaffolding.
JUST RELEASED
Vol. II MCAA Jurisdictional Disputes Manual
Volume II of the MCAA Jurisdictional Disputes Manual has been released and mailed to all MCAA members.
If you're in the mason contracting business, jurisdictional trade disputes can pose monumental problems causing work stoppages and costly delays. But many of the problems encountered can easily be resolved-if a common-sense approach is used. This is where the MCAA Jurisdictional Disputes Manuals come in to help you!
This 50-page edition is a valuable supplement to Vol. I, 3rd Edition, and contains the significant NLRB decisions that have been rendered since 1978 together with current arbitration cases. Special emphasis in this Volume is placed on the operation of forklifts and erection and dismantling of scaffolding.
This new and updated edition further contains a significant case from the Ontario Labour Relations Board.
Additional copies of Volume II are available at $5.00 per copy, plus $.75 for postage and handling, from the MCAA Executive Office, 17W601-14th Street, Oakbrook Terrace, IL 60181, (312) 620-6767.
MASONRY-NOVEMBER/DECEMBER, 1982 19