The building drainage pipe bundle assembly is a core integrated component of indoor and outdoor drainage, rainwater and sewage discharge systems in buildings. It consists of drainage pipes, pipe bundle supports, sealing connectors, reinforcement accessories and other parts, and undertakes the diversion and transportation of domestic sewage, rainwater and wastewater in buildings. Its selection adaptability and installation standardization directly determine the patency, anti-leakage capacity, seismic and noise reduction effect and service life of the drainage system. In accordance with Code for Construction Quality Acceptance of Building Water Supply, Drainage and Heating Engineering (GB 50242) and technical regulations for building drainage pipelines, this paper systematically sorts out the selection principles, itemized selection standards, standardized installation processes, acceptance specifications and construction precautions of building drainage pipe bundle assemblies, which are applicable to residential buildings, commercial buildings, office buildings and other various building drainage projects.
I. Selection of Building Drainage Pipe Bundle Assembly
The selection of building drainage pipe bundle assemblies follows the principles of "working condition adaptation, zoned selection, noise reduction and anti-blocking, compliance and durability". According to building functions, drainage medium, laying position (indoor/outdoor, vertical pipe/horizontal main pipe), drainage temperature and load conditions, the specifications of pipe materials, pipe diameters, connection modes and bracket assemblies are matched to avoid pipeline blockage, leakage, deformation, abnormal noise and other problems caused by improper selection.
1. Core Selection Basis
Basic working condition parameters of building drainage shall be clarified before selection as the core basis for assembly selection:
Drainage medium parameters: Distinguish domestic sewage, rainwater, air conditioning wastewater and kitchen high-temperature wastewater, and clarify the impurity content, normal water temperature and instantaneous maximum water temperature of the medium. Conventional domestic drainage is under normal temperature working conditions, while kitchen drainage involves instantaneous high-temperature wastewater, so high-temperature resistant pipe materials shall be selected pertinently.
Laying area parameters: The laying scenarios include indoor ceiling, pipe shaft, floor concealed laying, external wall exposed laying, basement horizontal main pipe, etc. Silent and lightweight pipe materials are preferred for indoor concealed projects, while aging-resistant, high-rigidity and high-pressure resistant pipe bundle assemblies are required for external walls and basements.
Drainage flow and slope parameters: Calculate the peak drainage volume according to the number of single-floor households, drainage points and catchment area of the main pipe, determine the pipe diameters of vertical pipes, horizontal pipes and main pipes, and match the spacing of pipe bundle supports to ensure stable pipeline slope and meet the requirements of gravity drainage.
Building load and seismic requirements: Lightweight and seismic-resistant pipe bundle assemblies shall be selected for high-rise and super high-rise buildings. The weight of assemblies in densely laid pipe shafts shall be strictly controlled to avoid excessive structural load and comply with the specifications of building seismic supports and hangers.
2. Itemized Selection Standards
2.1 Pipe Bundle Material Selection
Materials are selected according to building drainage scenarios, temperature resistance, noise reduction and anti-corrosion requirements. The mainstream pipe materials have clear applicable scenarios and fully comply with building specifications:
UPVC Drainage Pipe Bundle: Applicable to conventional domestic sewage and rainwater drainage in ordinary residential buildings and office buildings, with continuous drainage temperature ≤40℃ and instantaneous water temperature ≤80℃. It has the advantages of light weight, corrosion resistance and low cost. It can be used for indoor exposed laying and ceiling concealed laying. Special UV-resistant pipes or anti-corrosion and sun-proof coatings are required for outdoor exposed laying.
Silent PVC Pipe Bundle: Specially designed for silent areas adjacent to pipe shafts of bedrooms and studies and indoor ceilings of residential buildings. Its inner wall structure reduces drainage water flow noise effectively. It is suitable for residential buildings with high requirements for living comfort and is the preferred choice for home decoration and high-end commercial buildings.
Ductile Iron Drainage Pipe Bundle: Divided into Type A, Type B and Type W, it features high rigidity, impact resistance, fire prevention, noise reduction and long service life. Type A is applicable to floor vertical pipes and parts bearing water impact; Type B is suitable for large-space horizontal main pipes in basements; Type W adopts clamp connection without hot work, applicable to old building renovation and narrow pipe shaft construction, and is the core pipe material for high-rise buildings and fire-key buildings.
HDPE High-density Polyethylene Pipe Bundle: It has high toughness, settlement resistance and corrosion resistance, suitable for outdoor buried drainage of buildings and settlement-sensitive areas of basements, which can resist slight foundation deformation and prevent pipeline fracture and leakage.
2.2 Pipe Diameter Specification Selection
Pipe diameters shall be selected strictly according to building drainage points and catchment grades. The standardized configuration of conventional building drainage pipe bundle diameters is as follows:
Kitchen and bathroom branch pipes and single-point drainage: De50 and De75 diameters, suitable for hand basin, floor drain and vegetable sink drainage;
Residential kitchen and bathroom vertical pipes and floor branch pipes: De110 diameter, the most commonly used drainage pipe diameter in buildings, meeting the multi-point water collection demand of a single floor;
Unit main vertical pipes and floor horizontal main pipes: De160 and De200 diameters, suitable for multi-floor water collection and centralized discharge of large-flow rainwater and sewage;
Building outdoor main drainage pipes: ≥De200 large-diameter pipes shall be selected according to the drainage volume of the whole building to avoid blockage and overflow during peak drainage.
2.3 Connection Mode Selection
UPVC/PVC silent pipe bundle: Adopt socket bonding or rubber ring socket flexible connection. Bonding is preferred for indoor concealed laying, and rubber ring flexible connection is adopted for areas with large temperature difference to adapt to pipeline thermal expansion and contraction;
Ductile iron pipe bundle: Type A/B adopts flange connection with strong sealing performance and high stability; Type W adopts stainless steel clamp flexible connection with convenient construction and no hot work, suitable for renovation projects and narrow spaces;
HDPE pipe bundle: Adopt hot-melt butt welding or electric fusion connection with good integrity and anti-leakage performance, suitable for outdoor buried drainage working conditions.
2.4 Bracket Assembly Selection
The bracket assembly includes fixed brackets, sliding brackets, anti-sway brackets and load-bearing piers, and its specifications shall be matched according to pipe material types and pipeline laying methods:
Plastic drainage pipe bundle: Special plastic clamps and light-duty galvanized brackets are selected to avoid pipe damage caused by hard metal contact, with strictly controlled bracket spacing;
Cast iron and metal drainage pipe bundles: Galvanized steel fixed brackets and load-bearing supports are selected with high bearing capacity, suitable for large-diameter and large-load main pipes;
Anti-sway brackets must be added for high-rise and long-distance horizontal pipes to resist vibration caused by drainage water impact and prevent pipeline loosening and displacement.
3. Selection Verification Key Points
Item-by-item verification shall be carried out after selection: the pipe material temperature resistance shall adapt to drainage working conditions to prevent plastic pipeline softening caused by high-temperature wastewater; the pipe diameter shall meet peak drainage volume without water accumulation and blockage risks; the connection mode shall adapt to the laying environment; the bearing capacity and spacing of brackets shall match pipeline specifications; pipe materials and brackets in outdoor and humid areas shall have anti-corrosion and aging resistance, fully complying with building drainage acceptance specifications.
II. Installation Method of Building Drainage Pipe Bundle Assembly
The installation of building drainage pipe bundle assemblies strictly follows the construction principles of "model first, controllable slope, stable pier, reliable sealing, anti-sway and anti-leakage". The standardized construction process includes pre-installation preparation, benchmark setting-out, bracket installation, pipe bundle positioning and connection, sealing reinforcement, rectification and acceptance, focusing on four core indicators: drainage slope, interface sealing, bracket spacing and verticality.
1. Pre-installation Preparation
1.1 Assembly Inspection on Arrival
Verify that the specifications and models of pipe bundles, pipe fittings, brackets and sealing accessories are consistent with the selection scheme; check that the outer wall of pipes is free of cracks, depressions, burrs and discoloration, and the inner wall is smooth and unblocked; rubber sealing rings are complete without aging and deformation, and clamps, bolts and brackets are free of corrosion and defects; unqualified products are prohibited from construction.
1.2 On-site Cleaning and Setting-out
Clean sundries, dust and oil stains on the laying base such as pipe shafts, ceilings, wall reserved holes to ensure a flat and clean construction base; pop up the pipeline installation center line, slope control line and bracket positioning line according to the building drainage construction drawing, mark the accurate installation positions of vertical pipes, horizontal pipes, pipe fittings and brackets, control the setting-out accuracy to provide a benchmark for subsequent installation.
1.3 Tools and Consumables Preparation
Prepare levels, tape measures, ink lines, torque wrenches, hot-melt machines, pipe cutters, sandpaper, adhesives, lubricating soapy water and other tools and consumables; all adhesives, sealants and rubber rings shall be matched with pipe materials, adapting to normal temperature and conventional corrosion working conditions of building drainage.
2. Standardized Installation Process
2.1 Hanger and Bracket Assembly Installation
Hangers and brackets shall be installed first to ensure the laying slope and stability of pipe bundles, with strict compliance with spacing specifications: the spacing of horizontal pipe brackets for metal drainage pipes ≤2m, vertical pipe spacing ≤3m, and only one fixed bracket is required for vertical pipes with floor height ≤4m; the spacing of plastic drainage pipes shall be set according to pipe diameters to avoid pipeline sagging and water accumulation caused by excessive spacing.
Reinforced brackets must be added within 500mm at both ends of pipeline elbows, tees, elbows and interfaces; anti-sway brackets shall be installed for horizontal pipes with length exceeding 6m with a spacing ≤12m; C20 concrete load-bearing piers shall be poured at the elbow of vertical pipe bottoms to prevent vertical pipe settlement and interface cracking under stress. Brackets shall be closely attached to the base, the slope of horizontal pipe brackets shall be consistent with the designed pipeline slope, with vertical deviation ≤3mm/m and full-length deviation ≤10mm.
2.2 Pipe Bundle Positioning and Alignment
Lay pipe bundles in the sequence of "vertical pipes first, then horizontal pipes; main pipes first, then branch pipes". Ensure flat pipe cuts without burrs and cracks, and polish the inner and outer edges of pipe orifices with sandpaper after cutting to avoid scratching sealing rubber rings. During laying and alignment, ensure concentric pipe axis, aligned spigot and socket, and reserve a standard installation gap of 5mm to adapt to pipeline thermal expansion and contraction; forced alignment and skew positioning are prohibited.
2.3 Interface Sealing and Connection
Adopt corresponding standardized connection processes for different pipe materials: for UPVC pipe bundle bonding, evenly coat special adhesive on pipe orifices, quickly align and insert, and stand for full curing; for rubber ring socket connection, coat soapy water on the surface of rubber rings for lubrication, insert into the socket smoothly to ensure the rubber ring fits the clamp uniformly without offset and extrusion deformation. For W-type ductile iron pipe bundle connection, sleeve the stainless steel clamp first, align the pipe ends and fasten the bolts evenly in times to ensure tight sealing. For hot-melt connected pipes, strictly control the constant temperature of 260±10℃, match the heating time according to pipe diameters, and butt joint uniformly without rotation to ensure integrated interface forming and no leakage hidden dangers.
2.4 Slope Calibration and Reinforcement
Strictly control the slope of gravity drainage pipe bundles. The standard slope of indoor domestic sewage horizontal pipes: De50≥35‰, De75≥25‰, De110≥20‰, De160≥10‰. No reverse slope, flat slope, water accumulation and backflow are allowed. Adjust the bracket height after installation to calibrate the horizontal slope of pipelines, add reinforced brackets and anti-sway components for long-distance horizontal pipes and high-level vertical pipes, and fix all loose points.
2.5 Hole Sealing and Finished Product Protection
Seal the reserved holes of pipelines passing through walls, floors and pipe shafts in layers with fire-proof sealing materials and cement mortar, and make waterproof flanges at floor positions to prevent water seepage, odor transmission and fire failure; clean sundries inside pipelines after installation, block pipe orifices, and protect finished products to avoid pipeline blockage caused by sundries falling during subsequent construction.
3. Core Installation Accuracy Acceptance Standards
Vertical pipe verticality: deviation ≤3mm per meter, full-length deviation ≤10mm;
Horizontal pipe slope: comply with the standard slope of corresponding pipe diameters, no reverse slope, flat slope or water accumulation section;
Interface sealing: all connecting ports are free of looseness, cracking and leakage, with rubber rings in place accurately;
Supports and hangers: compliant spacing, firm fixation, uniform stress, complete anti-sway and load-bearing components;
Pipeline layout: neat and straight without distortion, sagging and protrusion, and accurate installation position of pipe fittings.
III. Water Test and Completion Acceptance
1. Water Flushing and Ball Passing Test
Water flushing and ball passing tests must be carried out after the completion of pipe bundle assembly installation in strict accordance with building acceptance specifications. Layered and sectional water flushing tests shall be conducted with continuous water supply for more than 5 minutes to check no leakage, no water accumulation and smooth drainage at pipeline interfaces, pipe walls and sealing positions; balls with corresponding pipe diameters shall be used for ball passing tests, which can pass through the pipeline smoothly without jamming and retention to verify pipeline patency.
2. Completion Acceptance Requirements
After the test is qualified, check construction documents, selection parameters and concealed engineering records to confirm that all pipe bundle assembly materials, specifications, installation processes and accuracy indicators are compliant, and the drainage system operates stably without leakage, blockage and abnormal noise before completing the completion acceptance.
IV. Common Construction Problems and Prevention & Control Measures
Pipeline water accumulation and poor drainage: Main causes include insufficient slope, local reverse slope and pipeline sagging caused by excessive bracket spacing; prevention and control measures: calibrate the slope with a level during installation, strictly control bracket spacing, and encrypt support points for long-distance horizontal pipes.
Interface leakage: Mostly caused by rubber ring offset, insufficient bonding, uneven bolt fastening and sealing ring scratch by pipe orifice burrs; prevention and control measures: polish pipe orifices before alignment, install rubber rings in place and lubricate uniformly, fasten bolts diagonally and in times, and ensure sufficient curing time after bonding.
Pipeline vibration and abnormal noise: Caused by missing brackets, insufficient anti-sway components and no piers at vertical pipe bottoms; prevention and control measures: add brackets at pipe fitting positions, install anti-sway brackets for long horizontal pipes, pour load-bearing piers at vertical pipe bottoms, and reinforce weak points.
Pipeline aging and damage: Caused by improper selection of outdoor pipes and lack of sun-proof and anti-corrosion measures; prevention and control measures: select UV-resistant pipes for outdoor exposed laying, apply protective coatings after construction, and conduct anti-rust and anti-corrosion treatment on metal brackets.
