Molding layering test method for cement lining of nodular cast iron pipe

Abstract

The invention discloses a ductile cast iron pipe cement lining forming layering test method, relates to the technical field of ductile cast iron pipe production processes, and aims to solve the problems that production line equipment cannot meet test requirements, and capital consumption for specially purchasing experimental equipment is large. The method comprises the steps that a lathe in a production workshop is adopted to simulate a lining coating machine, and a to-be-tested nodular cast iron pipe sample which is not coated with a lining is clamped on a clamp of the lathe; uniformly mixing cement, sand and water according to the proportion required by the test to prepare a required coating material, and putting the required coating material into the to-be-tested nodular cast iron pipe sample on the clamp; blocking openings at two ends of the to-be-tested nodular cast iron pipe sample with films and adhesive tapes; adjusting the rotation speed of the lathe fixture according to the test requirement, starting to rotate, recording the rotation time, taking down the lining coating sample after the rotation is finished, and analyzing the test result; related test research can be normally carried out, the research, development, purchase and maintenance cost of special equipment is saved, and the operation of a production line is not influenced.

Description

Technical Field

[0001] The invention relates to the technical field of ductile iron pipe production technology, in particular to a ductile iron pipe cement lining molding layering test method. Background Art

[0002] Ductile iron pipe cement lining is an important anti-corrosion measure, mainly used to isolate water and pipe body, prevent pipe body corrosion, and thus protect water quality. It is evenly spread and firmly adhered to the inner wall of the cast pipe through the centrifugal lining process.

[0003] The main equipment used for cement lining of ductile iron pipes is the centrifugal lining machine. The company hopes to conduct tests to verify and improve the production process, such as the process time of centrifugal lining, whether the raw material ratio of cement lining is appropriate, whether it can meet the process requirements, etc. However, the equipment on the production line cannot meet the test requirements. The production line can only line pipes of fixed lengths such as 5.5m or 6m. In addition, directly using the production line equipment will affect the production of the production line. The laboratory needs to re-purchase various types of centrifugal lining machines for lining tests, which will cost a lot of money. The utilization rate of these equipment in the laboratory is low, which is a great waste of funds. Therefore, a ductile iron pipe cement lining molding layered test method is urgently needed to solve this problem. Summary of the invention

[0004] The purpose of the present invention is to provide a ductile iron pipe cement lining molding layered test method to solve the problem that production line equipment cannot meet the test requirements and the capital consumption of special purchase of experimental equipment is large.

[0005] To achieve the above object, the present invention provides the following technical solution: a ductile iron pipe cement lining molding layered test method, including the following specific contents:

[0006] The lathe in the production workshop is used to simulate the lining machine, and the ductile iron pipe sample to be tested that has not been lined is clamped on the fixture of the lathe;

[0007] According to the required proportion of the test, mix cement, sand and water evenly to form the required coating material, and put it into the ductile iron pipe sample to be tested on the fixture;

[0008] Use film and tape to seal the openings at both ends of the ductile iron pipe sample to be tested;

[0009] According to the test requirements, adjust the rotation speed of the lathe fixture, start rotation, and record the rotation time. After the rotation is completed, remove the coated sample and analyze the test results.

[0010] Preferably, analyzing the test results includes observing the stratification state of the mortar using a metallographic device, and also includes measuring the strength of the coating lining using a pull-out tester.

[0011] Preferably, when the ductile iron pipe sample to be tested is clamped on the fixture, the center line of the pipe is kept horizontal.

[0012] More preferably in the above preferred solution, when the ductile iron pipe sample to be tested is clamped on the fixture, the concentricity of the sample and the rotation axis of the fixture is adjusted to ensure concentricity during rotation.

[0013] Preferably, the test method includes at least two methods for the same type of ductile iron pipe samples to be tested. The first method is to use the same coating material and adjust different fixture rotation speeds and times. The second method is to use different coating materials and use the same rotation speed and time.

[0014] Preferably, the control system of the lathe itself is used to regulate the start, time and end of the rotation so that the error is controlled at the same level.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The ductile iron pipe cement lining forming layered test method can be applied to cement lining tests of ductile iron pipes of various lengths. It is simple and convenient to use, and the speed and time can be easily adjusted and operated, which can meet the production needs for centrifugal lining tests.

[0017] 2. The ductile iron pipe cement lining molding layered test method solves the problem of making ductile iron pipe lining samples in the laboratory, especially since there is no corresponding dedicated molding equipment on the market. It avoids the investment in such high-speed rotating and clamping equipment in the laboratory, the required design, production, and later maintenance costs, and also avoids the disadvantages of using equipment on the production line directly for testing, such as affecting production and single model. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram showing the stratified state of the mortar observed by a metallographic device after the test in Example 1 of the present invention;

[0019] Figure 2 This is a diagram showing the stratified state of the mortar observed by a metallographic device after the test in Example 2 of the present invention;

[0020] Figure 3 This is a diagram showing the stratified state of the mortar observed by a metallographic device after the test in Example 3 of the present invention;

[0021] Figure 4 It is a schematic diagram of a working state during the test process of the present invention. DETAILED DESCRIPTION

[0022] A ductile iron pipe cement lining molding layering test method, including the following specific contents:

[0023] The lathe in the production workshop is used to simulate the lining machine, and the ductile iron pipe sample to be tested that has not been lined is clamped on the fixture of the lathe;

[0024] According to the required proportion of the test, mix cement, sand and water evenly to form the required coating material, and put it into the ductile iron pipe sample to be tested on the fixture;

[0025] Use film and tape to seal the openings at both ends of the ductile iron pipe sample to be tested;

[0026] According to the test requirements, adjust the rotation speed of the lathe fixture, start rotation, and record the rotation time. After the rotation is completed, remove the coated sample and analyze the test results.

[0027] Analytical test results included observation of mortar delamination using metallographic equipment and measurement of lining strength using a pull-out tester.

[0028] When the ductile iron pipe sample to be tested is clamped on the fixture, keep the center line of the pipe horizontal.

[0029] When the ductile iron pipe sample to be tested is clamped on the fixture, adjust the concentricity of the sample and the rotation axis of the fixture to ensure concentricity during rotation.

[0030] The test method includes at least two types for the same type of ductile iron pipe samples to be tested. The first method is to use the same coating material and adjust different fixture speeds and times. The second method is to use different coating materials and use the same speed and time.

[0031] The lathe's own control system is used to regulate the start, time and end of rotation to keep the error at the same level.

[0032] Example:

[0033] The test method in the above embodiment is adopted, DN300 ductile iron pipe is used as the sample pipe, and the test adopts the same coating lining material, such as Figure 4 As shown, the coated sample pipe is clamped horizontally on the lathe fixture, and after the cement lining material is placed, different fixture speeds and times are adjusted for different groups to conduct tests. The data and pull-out strength test results of the three groups of tests are shown in Table 1 below:

[0034] Table 1: Rotation speed and time and pull-out strength test results

[0035] Group Sand-cement ratio Water-cement ratio Rotation speed (RPM) Rotation time (S) Pull-out strength (MPa) Result determination (pulling>3Mpa) DN300-1 1 0.36 560 100 3.84 qualified DN300-2 1 0.36 560 40 3.79 qualified DN300-3 1 0.36 750 30 3.39 qualified

[0036] In addition, metallographic equipment was used to observe the stratification of the mortar for the three groups of samples after the test. The metallographic results of the three groups are as follows: Figures 1 to 3As shown, after adopting this method, relevant experimental research can be carried out normally, which not only saves the cost of special equipment research and development, purchase and maintenance, but also does not affect the operation of the production line.

[0037] The above are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined by the claims.

[0038] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

Claims

1. A ductile iron pipe cement lining molding layering test method, characterized in that: The specific contents are as follows: the lathe in the production workshop is used to simulate the lining machine, and the unlined ductile iron pipe sample to be tested is clamped on the fixture of the lathe; cement, sand and water are evenly mixed into the required lining material according to the required proportion of the test, and the lining material is placed into the ductile iron pipe sample to be tested on the fixture; the openings at both ends of the ductile iron pipe sample to be tested are sealed with film and tape; according to the test requirements, the rotation speed of the lathe fixture is adjusted, and the rotation is started, and the rotation time is recorded at the same time. After the rotation is completed, the lining sample is removed and the test results are analyzed.

2. A ductile iron pipe cement lining molding layered test method according to claim 1, characterized in that: The analytical test results include observing the stratified state of the mortar using a metallographic device, and measuring the strength of the coating lining using a pull-out tester.

3. A ductile iron pipe cement lining molding layered test method according to claim 1, characterized in that: When the ductile iron pipe sample to be tested is clamped on the fixture, the center line of the pipe is kept horizontal.

4. A ductile iron pipe cement lining molding layered test method according to claim 3, characterized in that: When the ductile iron pipe sample to be tested is clamped on the fixture, the concentricity of the sample and the rotating axis of the fixture is adjusted to ensure concentricity during rotation.

5. A ductile iron pipe cement lining molding layered test method according to claim 1, characterized in that: The test method includes at least two types for the same type of ductile iron pipe samples to be tested. The first method is to use the same coating material and adjust different fixture rotation speeds and times. The second method is to use different coating materials and use the same rotation speed and time.

6. A ductile iron pipe cement lining molding layered test method according to claim 1, characterized in that: The lathe's own control system is used to regulate the start, time and end of rotation to keep the error at the same level.

Images