The construction of building fire protection facilities is an important part of building equipment engineering, and it is an essential building installation project in buildings. With the continuous increase in the height and breadth of buildings and the continuous improvement of people's living standards, higher requirements are put forward for the safety of fire water, the reliability of water supply and the fire resistance of buildings, etc. These in addition to the design and material and equipment selection, to a large extent, the quality of construction and installation needs to be guaranteed. The quality of construction directly affects the normal operation of building fire protection facilities. From the daily construction quality supervision and inspection and project acceptance, there are still some problems in the construction process, the following building fire engineering construction of a number of common problems are analyzed.

First, the main existing quality of common diseases

(1) Production and installation of pipes and supports

1, the riser installation distance from the wall is too large or too small, does not meet the requirements, affecting the use and beauty;

These are two different images, one of the risers too far away from the wall, the other against the wall and not vertical.

The specification requires the minimum distance between the center line of the pipeline and the beam, column and wall:

Nominal diameter(mm) 　25　  　32　  　40　  　50　  　70　  　80　  　100　  　125　  　150　  　200　 

Distance(mm) 　40　  　40　  　50　  　60　  　70　  　80　  　100　  　125　  　150　  　200　 

2. The production and installation height of the riser pipe support does not meet the specifications:

 

Riser pipe support installation height from 800 mm to 2600 mm phenomenon, there is no installation, there are also two installation, strange, what kind of have, can meet the requirements of the specification is very few, most projects have this phenomenon. At the same time, when the bracket is made, the groove of the Angle steel faces upward, which affects the force and the appearance; The mounting part of the support is not hidden.

Specification requirements bracket installation height and number:

The distance between the pipe support and the ground or floor should be 1.5 to 1.8m. When the floor height exceeds 5 m, two supports should be installed and evenly arranged.

In order to standardize the installation and beauty, the installation height of the bracket is required to be 1.8 meters, and the installation position is between the pipe and the wall, and it is hidden as far as possible. At the same time, the groove of the Angle steel is required to face down, and the pipe card in the same place should be consistent.

3, horizontal layout of pipe support spacing and parts do not meet the requirements of the code;

  

                Bracket mounting skewed

  

        There is no bracket at the elbow tee

  

         Support non-corrosion protection              There is no anti-sway bracket at the end

The above figure shows various quality problems during horizontal pipeline installation: support is not anti-corrosion, support spacing is too large, support installation is skewed, there is no support at the elbow tee, there is no fixed support at the end of the nozzle, and the distance between the pipe hanger and the nozzle is too close.

The distance between pipe supports or hangers

Nominal diameter(mm)  　25　  　32　  　40　  　50　  　70　  　80　 

100  　125　  　150　  　200　  　250　  　300　 

Distance(mm) 　3.5　  　4.0　  　4.5　  　5.0　  　6.0　  　8.0　  　8.5　  　7.0　  　8.0　  　9.5　  　11.0　  　12.0　 

The type, material, processing size and welding quality of pipe supports, hangers and anti-swing supports shall comply with the design requirements and the provisions of the current national standards;

The installation position of the pipe support and hanger should not hinder the spray effect of the nozzle; The distance between pipe support, hanger, and sprinkler should not be less than 300mm; The distance between the nozzle and the end should not be greater than 750mm;

There should not be less than 1 hanger for each pipe section on the water distribution branch pipe and the adjacent two sprinkler heads. When the distance between the nozzles is less than 1.8m, the hangers can be set at different sections, but the spacing of the hangers should not be greater than 3.6m;

Brackets should be added within 300 mm at both ends of the elbow for horizontal pipe installation; A support must be installed at the lower elbow of the riser. Brackets should be added to the clamp, elbow and tee joints of the pipe groove connection to avoid the stress of the pipe groove.

Water distribution main pipes and water distribution pipes should be marked with red or red rings. The width of the red ring mark should not be less than 20mm, the interval should not be greater than 4m, and the ring should not be less than 2 places in an independent unit.

Hydrostatic test

When the design working pressure of the system is equal to or less than 1.0MPa, the water pressure strength test pressure should be 1.5 times of the design working pressure, and should not be less than 1.4MPa; When the design working pressure of the system is greater than 1.0MPa, the water pressure strength test pressure shall be the working pressure plus 0.4MPa.

The test point of water pressure strength test should be located at the lowest point of the system pipe network. When injecting water into the pipe network, the air in the pipe network should be drained and the pressure should be increased slowly. After the test pressure is reached and the pressure is stabilized for 30 minutes, the pipe network should have no leakage or deformation, and the pressure drop should not be greater than 0.05MPa.

The water pressure tightness test should be carried out after the water pressure strength test and pipe network flushing pass. The test pressure should be the design working pressure, and the pressure should be stabilized for 24h without leakage.

(2) Sleeve installation is not standardized;

   

  

The above figure shows various phenomena when the pipe passes through the floor, such as the casing is not anti-corrosion, the gap between the casing and the pipe is not uniform, the bottom of the casing and the roof are not uneven, and the upper part of the casing is not higher than the floor.

Specification requirements: pipe through the floor, wall to place the casing, the size of the casing should be larger than the pipe two numbers; The bottom of the casing through the floor is flat with the roof, the top is 20 mm higher than the floor, and the bathroom is 50 mm higher than the floor; Both ends of the casing placed in the wall should be flat with the wall, and the gap between the casing and the pipeline should be filled with non-burning materials. The inner and exposed parts of the casing should be treated with anti-corrosion; The hole around the casing should be poured by layers of concrete one larger than the original floor plate label.

(3) The installation height, method and piping support of fire box and fire hydrant do not meet the specifications

 

The above pictures show that the hydrant mouth distance from the ground and the size from the bottom of the box do not meet the standard requirements, the hydrant head is not on the side of the door opening, the aluminum alloy door frame of the concealed box is buried in the wall, the dark box box is inconsistent from the wall, and the horizontal branch pipe of the hydrant is not installed with a support.

Standard requirements: the fire hydrant mouth (center) should be 1.1 meters away from the ground, not less than 140mm away from the side of the box, 120 mm to 140mm away from the bottom of the box; Fire hydrants should be installed on the open side of the door. The vertical pipe and horizontal pipe of the branch pipe of the fire hydrant should be installed with pipe supports.

Install the correct picture

(4) Alarm system equipment installation and line installation do not meet the specifications

 

The hand button is not firmly fixed, only one screw is fixed

 

The fire hydrant button is not firmly fixed, and the line is equipped with no pipe protection

 

The smoke detector is mounted on a support and suspended from the line

Code for automatic alarm construction acceptance

1, pipe laying and threading requirements:

★ Threading in the tube or trough should be carried out after the completion of the building plastering and ground works. Before threading, remove the water and debris in the pipe or trough. There should be no joints or kinks in the pipe or groove of the wire.

★ When the pipeline exceeds the following length, a junction box should be installed at the convenient connection point:

First, the length of the pipe exceeds 45m, no bending;

Second, the length of the pipe exceeds 30m, there is 1 bending time;

3. When the length of the pipe exceeds 20m, there are 2 bends;

4. Every time the length of the pipe exceeds 12m, there are 3 bending times;

★ When the pipe is in the box, the outer side of the box should be covered with lock, and the inner side should be installed with guard. When laying in the ceiling, the inner and outer sides of the box should be covered with lock.

★ After the wire of the automatic fire alarm system is laid, the insulation resistance of the wire of each loop should be measured with a 500V megohm meter, and the insulation resistance value should not be less than 20M.

★ The installation position of the spot fire detector should comply with the following provisions:

First, the horizontal distance between the detector and the wall and beam side should not be less than 0.5m.

Second, there should be no occlusions around the detector within 0.5m.

3. The horizontal distance between the detector and the air supply port of the air conditioner should not be less than 1.5m; The horizontal distance to the orifice of the perforated air supply ceiling should not be less than 0.5m.

Fourth, when the detector is set on the ceiling of the inner walkway with a width less than 3m, it should be arranged in the center. The installation spacing of the temperature detector should not exceed 10m; The spacing between smoke detectors should not exceed 15m. The distance between the detector and the end wall should not be greater than half of the detector installation distance.

5, the detector should be installed horizontally, when it must be inclined to install, the inclination Angle should not be greater than 45 degrees.

★ The "+" line of the detector should be red, the "-" line should be blue, and the remaining lines should be distinguished by other colors according to different uses. However, the color of wires for the same purpose in the same project should be the same.

★ The external wire of the detector base should have a margin of not less than 15cm, and there should be a clear sign at the entry end.

The cable holes of the detector base should be blocked. After the detector base is installed, take protective measures.

The detector's confirmation light should face the direction of the main entrance that is easy for human observation.

The detector can be installed only when it is about to be commissioned. Before installation, keep it properly and take measures to prevent dust, moisture, and corrosion.

(5) Failure to take protective measures for semi-finished products on site

The box installed before the wall painting has not taken protective measures, especially the semi-bright and semi-dark box, the cement and mortar pollute the box when painting, which is difficult to remove, resulting in the need to re-paint the work.

The line into the box does not use the hole opener, with the hair chisel, damage the box

(6) Common problems of pipeline system and solutions

The quality of the HVAC project depends not only on the level of design and the performance of the equipment, but also on the quality of the entire ventilation and air conditioning system, which also includes the connection of pipes and components. The quality of the pipeline system is common and the most common. In accordance with the requirements of quality specifications, the following measures and methods are put forward for the prevention and control of common problems in the pipeline system, components and other aspects of HVAC engineering.

1. Production and installation of air duct system

The air duct is made of thin steel plate. Common quality problems include uneven installation of the air duct. The main manifestations are:

(1) the steel degree of sheet steel duct is not enough;

(2) the surface of the large edge of the air duct sinks;

(3) The air duct is not tight and the riveting is not strict (as shown in Figure 1);

Figure 1

(4) The flanging width of the air duct is inconsistent (Figure 2);

Figure 2

(5) The air duct flange sealing gasket connection does not meet the requirements (as shown in Figure 3).

Figure 3

The consequences of the above phenomenon: when the system is running, the air leakage on the surface of the duct is large and vibrates to produce noise, which will not only cause environmental noise pollution, but also reduce the service life of the duct; The appearance of the air duct system is not beautiful, and the loss of cold heat is increased.

Analysis of the causes:

(1) The thickness of the steel plate for making the air duct does not meet the requirements of the construction and acceptance specifications;

(2) no reinforcement measures have been taken;

(3) uneven sheet feeding;

(4) the size deviation between the air duct and the flange is too large;

(5) The material of the flange gasket does not meet the specifications.

Preventive measures:

(1) The thickness of the steel plate for the production of the air duct, if the drawings have no special requirements, must comply with the relevant provisions of the current "Ventilation and air conditioning Engineering Construction Quality Acceptance Code" GB50243-2002;

(2) Reinforcement measures can consider Angle steel reinforcement, corrugated reinforcement and galvanized wire rod reinforcement;

(3) It is best to use mechanical blanking when the rectangular plate is blanking. Before blanking, the measurement is accurate, the bite joint is uniform, and there should be no holes or cracks. If there is a sealant, it can be blocked.

(4) In order to ensure the quality of pipe fittings, before the air pipe is inserted into the flange, the flanging size should be strictly determined to achieve no distortion and smooth flanging;

(5) The material of the flange gasket should be selected in strict accordance with the requirements of the specification, such as non-combustible materials can be used for smoke exhaust duct.

2. Prevention and control measures

1, strictly implement the relevant national construction and acceptance specifications, enterprise technical specifications. National standards are building fire design, construction and supervision must follow the criteria, China's current introduction of a large number of norms and technical standards, not only integrated the advanced experience of the world's developed countries, some or the lessons of the blood summed up the results, if not strictly implemented, will repeat the mistake, regret too late.

2, to urge the construction unit to strictly perform the responsibility of safety production, strengthen the management of subcontracting units. From engineering design, engineering construction, engineering supervision and other aspects of strict control, to ensure safety, eliminate all kinds of hidden dangers of accidents.

3. Fully implement the new fire management mechanism of "government leadership, industry management, enterprise responsibility, and supervision by public security fire agencies according to law". Each performs its own duties, each assumes its own responsibilities, and works together to form a seamless three-dimensional management network and fire safety barrier for fire safety, and does not give anyone who violates national fire laws, regulations and technical norms an opportunity to take advantage of it.

4, pay attention to the construction practitioners related to safety production technical standards, construction site safety operation and other aspects of training. Strengthen fire safety publicity, education and training, and further improve the design, construction, supervision and fire control supervision and management of building fire control facilities. At present, the comprehensive fire safety education and training widely carried out at all levels and places has received certain results, but the level of fire knowledge of professionals needs to be further improved, and the ability to find and solve problems needs to be further strengthened.

Practice has proved that as long as the quality awareness is strengthened, the construction management is strict, and the construction is carefully carried out in accordance with the norms and operating procedures. With the continuous improvement of the long-term restriction mechanism of construction project approval, design, construction, supervision, completion and acceptance, and the continuous improvement of fire protection regulations, the increasing awareness of fire protection laws, and the improvement and improvement of the overall installation technology level, it will build the project that the country and the people can rest assured.

Email:
tfjlgs@126.com

Service Hotline:
+86-316-2181351

Address:
9-1-1303, West District, Eighth Avenue, Guangyang District, Langfang City