Concrete sewer pipes
Concrete pipes in sewage system, specifications, standards
General information about concrete pipes
Concrete sewer pipes that are used in collection network and sewage and rain’s water transfer lines are in two types; simple and armed. It should be noted that sewage with non-circle cross section is not mentioned in this discussion. Installing concrete pipes with a diameter of 1000 mm produced by baverce company.Concrete pipes standards:There are different standards for production and application of concrete sewer pipes. here are some of the most important standards in the following; which does not mean that producing concrete sewer pipes is limited to these standards; but means that most of the countries in the world have provided some standards about and use valid standards and cite this standards.-standards no. DIN 4032 and DIN 4035 for producing concrete pipes and accessories.-Standard no. ASTM C14M and ISIRI 8906 for producing armed concrete sewer pipes in 5 classes |, ||, |||, |V, V-Standards no. ASTM C655M and ASTM C506M for producing armed concrete sewer pipes-Standard no. ASTM C443M for connection between concrete sewer pipes with plastic ring
Application of concrete pipes
Concrete sewer pipes in different diameter have a lot of use in connection network, transfer lines and also sewer pomp lines. Today with the development of petrochemical industries and wide production of poly ethylene, the use of concrete pipes –specially in a diameter up to 400 mm; which is about 80% length of swage pipes in average – have reduced and poly ethylene have replaced them. Concrete sewer pipes in to simple and armed types, in different size with a diameter between 400 and 2450 mm produced by vibration and press method. Armed concrete sewer pipes are so suitable for collecting rain and sewer.The amount of bar needed for concrete sewer pipes production depends on tube thickness and diameter, The more thickness and diameter of the pipe, the more the rebar should be used to increase the resistance of the tube.Simple concrete sewer pipes with a diameter up to 900 mm are producible, but using them in a stomach more than 600 mm is not normal, without making this point limiting this.
Production of concrete pipes
Concrete sewer pipes should be produced based on one of the valid standards, with equipment and special machines in factories and with proper quality control; and should be tested before being transported to workshop.Production of concrete pipes in a workshop is not allowed under no circumstance and this kinds of pipes should not be used for sewer connection network. Simple and armed concrete sewer pipe classify in 5 classes |,||, |||, |V, V based on standard. This classification is based on maximum pressure for crushing stone which naturally affects The pipe’s depth and the sub-grade’s type. For producing concrete sewer pipes, sulfate resistance cement is used
Simple concrete sewer pipes
As said before, simple concrete sewer pipes to a stomach up to 900 mm is producible but in Iran simple concrete sewer pipes don’t have a diameter more than 600 mm. Advices in different Iranian publications number- 146A institute water engineering standard design, also didn’t recommend using simple concrete pipes with a diameter more than 600 mm. according to installation terms and bearing tube pressure while transportation, the length of each concrete pipe is Limited.
Armed concrete pipes
Armed concrete sewer pipes according to their class, have one or two layer of bar. Bars are frame made in factories and installed in form. Bars basket is made by machines the length of each armed concrete sewer pipes is normally 2 or 2.5How to carry produced armed concrete sewer pipes
Armed concrete sewer pipes are normally build in two ways
1-The concrete is poured into the tube and vibrated to be dense concrete; then extricated and released in a wet place to become stiff and hard
2-Loose plastic concrete is poured into the rotating steel tube with a gutter with a small slope. The concrete will be thrown to the tube walls, in the beginning the coarse grains collapses to the bottom of the steel tube and fine-grained concrete (mortar) sticks to the wall. Because the steel tube rotate regularly; the coarse grains will be thrown to the walls and put in the mortar.
Processing with vapor
Acting with vapor is done by injecting vapor. Armed concrete sewer pipes can be put in vapor processing room. The tube must be released in the room for a specific time and temperature to obtain the desired resistance. The processing room must be designed in a way that vapor could circle around the body of the tube and be safe from any suction caused by external air flow.
Concrete pipe jacking
Pipe jacking doesn’t have any disturbance for underground pipes installation. This is a very efficient method for long and short pipe’s lines (in 150 meter distance between jack establishment stations) and for pipe passing under main ways, roads and rail; which is much more efficient than other ways. Nowadays because of population increase, the close proximity of the apartments, buildings and urban facilities, and the resulted in traffic; pipe jacking is an efficient and suitable replacement for the old ways.Specifications of pipe jacking tube1-The pipes are produced according to standard ASTM-C76.2-Pipes have gasket metallic ring 3-Pipes comes in 350 units and made by anti-sulfate cement4-Inside the pipe is covered by poly ethylene page or GRP; depending on the costumer’s commands5-Pipes are produced from size 1000 to 2400Baverce company’s concrete pipe jacking are produced from 600 to 2400 diameter special metallic ring.
Corrosion and protection covers of concrete pipes
Concrete sewer pipes should be made with anti-sulfate concrete, but this case doesn’t mean that it will protected from corrosion
Protection cover of the external surface of the pipe
If the soil of the installation site of pipes was corrosive or the pipe touches the corrosive groundwater, protection cover for the external surfaces is necessary. Protecting external surface of the concrete pipes in order to protect them from penetration of corrosive materials and destruction of rebar layers has more importance.Protecting external surface of concrete pipes depending on the corrosiveness of the water and soil path can be in different ways; interchanging the surrounding corrosive soil with suitable non corrosive soil such as mixed river path or sandy soil, or tar felting external surfaces. Banding strip and lathering is not common or necessary. If the external surface of the pipe is going to be covered in the workshop the contractor must do the whole operation according to the design information and the standard way of using the materials in the protection cover and the consulting engineer
.3-2-7-3 protective cover of the internal surface of the pipe
Existence of H2S gas on top of the liquid in the sewage produces acid and according to the time, temperature, flow amount and the amount of sulfate in the sewage, cause corrosiveness in the internal surface of the pipe specially on the top part. Because the amount of liquid changes all the time, most part of the pipe is in danger of corrosiveness and normally, about 15 percent of the internal surface of medium and large pipes is covered by the liquid and doesn’t face the danger of corrosiveness of H2S gas. For sub sewer pipes in medium and big cities the diameter is less than 400 mm and make most length of the network the above number is less than 15.Best thing for protecting internal surface of the sewer pipe nowadays, is using poly ethylene plates which will be put in the pipe during the production. This plates will be put and covered in the concrete by the tentacles which are in one side of the plate. In the connection site, with prediction of extra edge on one side of the tube and cutting the tentacles behind them, extra part of the tube will be on the internal edge of the front tube, connected and will be welded by the special device to integrate the cover of the pipe lines. Welding this plates in the connection site normally is available for pipes with a diameter of 400 mm or more and so this covers are used for pipes with a diameter more than 400 mm.