Knowledge！Key points for HVAC pipe installation project construction

Ventilation and air conditioning:

(1)The materials used in the manufacture of air ducts must meet fire protection requirements. The body, frame, fixing materials and sealing materials of fire-resistant air ducts are non-combustible materials. The covering material of the composite air duct is non-combustible material, and the internal insulation material should be non-combustible or flame-retardant B1 grade and non-toxic to the human body.

(2)The pressure of the air duct system is a high-pressure system and an ISO1~5 level (above the joint number standard level 100) purification system. The medium-pressure system and the smoke exhaust, dust removal, low-temperature air supply system and the ISO6~9 level (below the US federal standard level 1000) purification system.

Different air pressures in ducts have different requirements for the spacing of duct flange bolts and rivets, the way of biting, and the method of splicing.

(3)When ducts pass through walls, pay attention to the setting of the casing, especially when passing through fireproof, explosion-proof walls and floors. The casing material must be greater than or equal to 1.6 mm. (4) When installing duct brackets with a side length greater than 630 mm, if expansion bolts are used for fixing and the bolts are subject to tension, it is best to set 2 or more expansion bolts for each duct. All profiles cannot be cut with oxy-acetylene flames, nor can they be opened with oxy-acetylene flames. The insulation pad in the bracket must be well fixed to the bracket profile.

(4)When installing fire dampers, pay attention to the installation direction, and the temperature sensing element must be on the windward side. When the long side length or diameter is greater than or equal to 630 mm, an independent support and hanger should be installed. The distance from the fire partition wall should not be greater than 200 mm. A manual test should be performed after the system is installed. The insulation material of the fire damper should be non-combustible.

(5)When installing combined air conditioners in air conditioning and ventilation equipment, ensure that the gaps are sealed. The equipment has complete seismic isolation measures. The equipment has exposed running transmission parts that are safely protected.

(6)The number of insulation nails must be guaranteed. (8, 10, 16/m2) The insulation material must not have a "cross" joint. The insulation material should be non-combustible and B1 grade flame retardant material, but the fire damper, the fire wall, the electric heater and the front and rear 800mm must be non-combustible materials. The gaps between the insulation material and the support, valve, flange and other accessories must be tight.

Insulation materials with a certain strength should be installed at the supports and hangers, and corresponding anti-corrosion measures should be taken. Non-closed-cell materials should have a moisture-proof layer, and the overlap of the moisture-proof layer should not be less than 30mm. Hard materials should be tight and without gaps. The insulation of the vertical pipe should pay attention to water flow. Attention should also be paid to the insulation and moisture-proofing of the soft joints.

Pipeline construction:

(1)Supports and hangers When making support and hanger profiles, gas cutting shall not be used. If gas cutting must be used for on-site construction, the cut surface shall be polished smooth. Gas cutting shall not be used to open holes in profiles. When the supports of stainless steel pipelines are made of carbon steel, protective measures (galvanizing, chrome plating or polytetrafluoroethylene spacers) shall be taken on the steel surface. The forms of the supports for the same project should be as consistent as possible. Equipment and other pipelines shall not be used as components of the supports. The supports shall not be directly welded to pipelines, pipe fittings or valves. When non-metallic composite pipelines use metal supports, non-metallic pads or sleeves shall be added between the pipeline and the support.

(2)When installing the casing, a casing must be installed when the pipe passes through the wall and the floor. The casing passing through the floor should be 20mm above the ground, and the casing passing through the bathroom and kitchen should be 50mm above the ground. The gap between the wall casing and the pipe should be filled with flame-retardant dense material, and the gap between the floor casing and the pipe should also be filled with waterproof grease.

(3)Galvanized pipes for pipe connection shall not be welded. Pipes less than or equal to 100mm should be connected by threaded connection, and pipes greater than 100mm should be connected by flange or ferrule. The welding point with the flange should be galvanized twice. The outer diameter of the stamped elbow used on the pipe should be the same as the outer diameter of the pipe.

(4)The connection of the insulation layer bracket of the insulated pipe should use insulation materials with a certain strength and density, and the fixing method of the bracket to the bracket must be firm.

For the insulation of the "Y" type filter, a convenient opening insulation method should be set at the filter screen removal port. It is best to use a high-necked valve on the valve on the chilled water pipe to prevent condensation on the handle. The insulation layer should be tight and seamless, especially the joints between the pipe and the pipe fittings, flanges, and valves should be carefully laid. Non-closed-cell insulation materials should be laid with a moisture-proof layer. The overlap of the moisture-proof layer should be uniform and wrinkle-free, and the overlap width should not be less than 30mm.

(5)Pipeline markings The machine room, pipeline wells and other pipelines with a wide variety of media and exposed pipelines must have pipeline markings. The pipeline markings must indicate the flow direction and the name of the medium. The color must meet the design requirements. If there are no design requirements, they must be implemented in accordance with national standards.

Project data:

1.Ventilation and air conditioning

(1)Technical briefing According to the actual situation of the enterprise, prepare briefing records for the air duct processing, accessory processing, air duct system installation, equipment installation and testing, and commissioning stages. The briefing record must be targeted. Matters that are not involved in or do not exist in this project must not be included in the briefing content. The briefing record is for the construction operation layer. Do not include vague contents such as "according to design requirements" or "according to specifications GB×××". The briefing record is for the construction operation layer. Do not include vague contents such as "according to design requirements" or "according to specifications GB×××".

(2)Material quality certification equipment, material certificates, and main material quality certification documents must be complete and clear. The material quality certificate must be attached to the material inspection form. The inspection form must indicate the time of entry, quantity, quality, and be signed by the supervision engineer. Equipment, material certificates and quality certification documents should preferably be originals. If this is difficult, the original storage location can be indicated on the photocopy, and the original storage unit shall affix a red seal (be careful not to use duplicate copies, i.e. copies that have been stamped). For materials related to fire safety, there must be corresponding certification documents, such as fire resistance test reports for thermal insulation materials, fire inspection certificates for smoke exhaust fans, etc.

(3)Construction process documents should pay attention to the authenticity and validity of the documents. The records of construction logs, hidden projects, quality inspections, etc. should be complete, and the time should correspond to the construction sequence. The records of hidden projects should be detailed, with a simple diagram attached, and additional drawings can be attached if necessary. Do not use words such as "see design drawing No. ××". The application of new processes and new technologies is a highlight and an important bonus factor in project evaluation. Keep good records of equipment installation.

(4)Test and test records The light transmission test is a tightness test for low-pressure systems (≤500Pa). The specific measures for creating a dark environment and the specific models and specifications of the testing tools should be indicated in the records. No vague descriptions such as "light bulbs below 36V and greater than 100W" should appear. The manual test of fire dampers is an important measure to ensure the installation quality of fire dampers and verify their reliable operation. The air-conditioning system should be debugged in summer and winter conditions respectively. Electronic and pharmaceutical construction projects should pay attention to the requirements of purification projects, system pressure, rivet spacing, flushing records, etc. Pharmaceutical projects must also comply with GMP regulations and do a good job of sedimentation bacteria detection.

2.Pipeline

(1)Materials Materials must have quality certification documents (certificate of conformity or material certificate). If the quality certification document is a photocopy, the storage location of the original and the official seal (red seal) of the storage unit must be indicated. The certificate of conformity and other quality certification documents must be attached to the material inspection form and the quantity must be indicated. Domestic water supply pipelines and their fittings and other related materials must be issued by the health and quarantine department and meet the test report for domestic drinking water. If galvanized steel pipes are welded on site, the corresponding valid secondary galvanizing certificate (contract and quality inspection certificate) must be provided. If seamless steel pipes are used, their application scope must be distinguished. When seamless steel pipes are used to transport fluid media, "seamless steel pipes for fluid media GB8163" should be selected, and "seamless steel pipes for structures GB8162" should not be used. Fire protection products must have a fire protection test report issued by the fire department, and pay attention to its validity period (coinciding with the purchase time). Insulation materials must have a combustion performance test report.

(2)Technical disclosure New processes, new technologies, and new materials must be disclosed separately. The content of the briefing should be targeted, and the scope of a briefing record should not be too broad. According to the specific situation within the enterprise, special briefings should be made for problems that are prone to problems or are easily overlooked by construction workers or processes with high technical requirements, such as the production of pre-buried wall sleeves; the fixing of vertical pipes in high-rise buildings; pipeline flushing plans, debugging plans, and lifting plans for large equipment.

(3)Inspection and test records The strength test (1.5Pg) and tightness test (1.1Pg) of valves before installation. The appearance inspection record of pipeline welds should check the weld height, undercut, cracks, pores, slag and other defects. The data recorded in the pipeline strength test should be true, and the pressure drop value should not exceed the accuracy of the pressure gauge. It is best to attach a pressure gauge calibration record. For non-pressure pipelines and drainage pipelines, fill the water for 15 minutes and then add water for 5 minutes. Drainage risers and horizontal main pipes should be tested for ball passing. The ball passing record should indicate the value of the ball passing diameter instead of writing "greater than 2/3 of the pipe diameter". Fire hydrant test records, one fire hydrant on the roof or water tank room and two fire hydrants on the first floor are tested. The spout of the box-type fire hydrant faces outward and should not be installed on the door axis side. For domestic water supply, water samples should be taken and sent to the relevant departments (preferably the local health and quarantine department) for testing, and a report that it meets the drinking water standards should be issued.

For non-pressure pipes and drainage pipes, fill them with water for 15 minutes and then observe for 5 minutes. Drainage risers and horizontal main pipes should be tested with a ball. The ball record should indicate the value of the ball diameter instead of "greater than 2/3 of the pipe diameter". Fire hydrant test records, one fire hydrant on the roof or water tank room and two fire hydrants on the first floor should be tested. The spout of the box-type fire hydrant faces outward and should not be installed on the door axis side. Samples should be taken for domestic water supply and sent to the relevant department (preferably the local health and quarantine department) for testing, and a report that it meets the drinking water standards should be issued.