CN102183407B - Method for inspecting reinforced thermoplastic pipe based on designed life - Google Patents

Abstract

The invention relates to the field of design and inspection of reinforced thermoplastic pipes (RTP) and aims at providing a method for inspecting the reinforced thermoplastic pipe based on the designed life. The method comprises the following steps of: performing bursting test on the RTP; performing puncture test on the RTP; performing tensile test on a reinforcement material of the RTP and a base body material of the RTP; obtaining a long-time burning pressure Plife of the RTP based on the designed life; and finally comparing a relation between the long-time burning pressure Plife and a designed pressure Pdesign, if Plife is greater than or equal to K'Pdesign, determining that the product is qualified. By the method, the burning pressure under long-time service life of the RTP can be forecast and inspected by short-time test, so the working procedure of performing a large amount of long-time hydrostatic test in the conventional long-time hydrostatic intensity measurement method based on an extrapolation method, so the RTP production cost is saved, the production period is shortened, and the reliability and the product competitiveness of the RTP are enhanced.

Description

The method of inspection based on the reinforced thermoplastics complex pipe of designed life

Technical field

The present invention relates to design and the check field of reinforced thermoplastics complex pipe, particularly relate to the method for inspection based on the reinforced thermoplastics complex pipe of designed life.

Background technology

Reinforced thermoplastics complex pipe (Reinforced Thermoplastic Pipe is called for short RTP) is in recent years new development, and relatively traditional metallic conduit or plastic conduit have the novel tube of significant advantage.It combines the characteristics such as the pliability of the high strength of reinforcing material and matrix material and corrosion resistance, so it not only can bear very high working pressure, and is keeping simultaneously the toughness as the similar polyethylene pipe.RTP is generally three-decker: internal layer is the thermoplastics such as high density polyethylene (HDPE); The middle layer is the enhancement layer that is made of steel wire or other high strength fibres; Skin is the protective seam that the thermoplastics such as HDPE consists of.Because the design feature of RTP uniqueness makes it integrate the advantage of traditional metal pipeline and plastic conduit, therefore can be applied to the engineering of the rugged surroundings operating modes such as various high pressure, corrosion and large deformation.

At present, RTP pipe has been widely used in the association areas such as the oil, chemical industry, urban construction of China, as oil gas carry, the mud mineral products are carried and water supply etc.Along with Development of Marine economy in " 12 " planning, formulate and implement the proposition of ocean development strategy, China starts to develop the resources such as marine oil and gas abundant under 3,000,000 square kilometres the marine site and mineral products.Carry the pipeline of seabed resources owing to be faced with a series of mal-conditions such as bathycurrent disturbance, high pressure, microbial attack and chemical corrosion, thereby require the RTP pipeline to have higher reliability.

In recent years, the Xie Xia of Tianjin University of Technology etc. has carried out theoretical analysis and experimental study to fiber winding composite tube, has proposed the Forecasting Methodology of tubular axle combined compressive strength for line contact.The Zheng Jin of Zhejiang University ocean, Tang Renzhong etc. carried out mechanical property to the steel wire winding reinforced plastic pipe, based on the design of intensity and the research work of optimization method, propose the strength and stability analytical approach of complex pipe, thereby established theoretical foundation for the Secure Application of complex pipe.These theoretical models and achievement in research are used for instructing production practices gradually, for the safe handling of RTP pipe provides technical support.

Yet along with the expansion of RTP usable range and the increase of tenure of use, the problem in serviceable life also more and more received publicity when it was long.The design of present stage RTP pipeline and check or main reference are used for reference design or the method for inspection of steel pipe or plastic tube.As check steel wire winding reinforced plastic pipe among the standard C J/T 189-2007 of the Ministry of Construction " steel wire mesh frame plastic (tygon) composite pipe and pipe fitting " still with reference among the GB15558.1 " Buried PE Gas Pipe road system part 1: tubing " to the examination requirements of PE pipe, do the 165h withstand voltage test of 20 ℃ and 80 ℃.The high temperature accelerated test method is also adopted in the domestic and international research that RTP is relevant mostly, then adopt standard extrapolation method (ISO9080 Plastics piping and ducting systems--Determination of the long-term hydrostatic strength of thermoplastics materials in pipe form by extrapolation, corresponding Chinese Industrial Standards (CIS) is GB/T 18252 plastic duct systems with the mensuration of extrapolation method to the long-term hydrostatic strength of thermoplastic plastic pipe) prediction tubing whether can reach the serviceable life in 50 years.But in fact the RTP pipe is not identical with the bearing mechanism of HDPE pipe: RTP manages under arms and mainly bears load by reinforcing material in the process, and matrix material wherein occurs to relax along with increasing service time gradually; And HDPE manages and bears load by the HDPE body in the process under arms always, and it is slowly creep and be accompanied by the phenomenons such as wall thickness reduction in use.Therefore, existing this when long for RTP the method for inspection in life-span can only increase on foot the cost of product, but quality control is not had useful effect.RTP is in the urgent need to having suitable life prediction and the method for inspection.

Summary of the invention

The technical problem to be solved in the present invention is, overcomes deficiency of the prior art, and a kind of method of inspection of the reinforced thermoplastics complex pipe based on designed life is provided.

Be the technical solution problem, the technical scheme that the present invention takes is:

A kind of method of inspection of the reinforced thermoplastics complex pipe based on designed life is provided, may further comprise the steps:

(1) RTP explosion bulge test: by the quick bursting test, measure the average burst pressure P of RTP _bAnd corresponding average blasting time t _b

(2) RTP withstand voltage test: RTP is suppressed rapidly to a certain set pressure, then keep this pressure until the RTP explosion is adjusted set pressure to control pressure-resistant time at 72～10000 hours; Measure average burst pressure P _n, logarithm blasting time average t _1nAnd logarithm square blasting time average t _2n

(3) reinforcing material of RTP carried out tension test, measure the mean value ε of its breaking elongation _f

(4) matrix material of RTP is carried out tension test, first with constant rate of strain

Be stretched to strain stress _gAfter, keep again 30min, measure matrix material at the force rate h of lax front and back;

Described ε _gChoose as follows:

(a) if the reinforcing material of RTP be just anticlinal around steel wire or aramid fiber material, then

${\mathrm{\ϵ}}_g=\frac{{\mathrm{\ϵ}}_f}{{\cos }^2\mathrm{\θ}}---(8-a)$

(b) if the reinforcing material of RTP is composite bed, then

ε _g＝ε _f (8-b)

In the formula, θ is reinforcing material and winding angle perpendicular to the axis plane;

The rate of strain that described matrix material stretches

Calculate as follows:

Burst pressure P when (5) long based on the RTP of designed life _LifeFor:

P _life＝P _b-K·(P _b-P _n)；

$K=\frac{h-(B_1\·{\lg }^{2}x+B_2\·\mathrm{lgx}+B_3)}{h-(A_1\·t_{2n}+A_2\·t_{1n}+A_3)}$

In the formula, x is the serviceable life of designing requirement, unit: year; Described A ₁, A ₂, A ₃, B ₁, B ₂, B ₃Be according to the matrix material material and definite coefficient;

Burst pressure P when (6) long _LifeWith design pressure P _DesignRelation, if P _Life〉=K ' P _Design, judge that then product is qualified; Wherein K ' is the safety coefficient definite according to use occasion.

Among the present invention, in RTP explosion bulge test and RTP withstand voltage test, test temperature is set as the environment temperature T when RTP is actual to be used _a, test is carried out in air, and the medium in the sample is water or actual fed medium.

Among the present invention, in the tension test to RTP reinforcing material and matrix material, test temperature is set as the environment temperature T when RTP is actual to be used _a

Beneficial effect of the present invention is:

The present invention is based on architectural feature and the mechanical behavior of RTP uniqueness, propose design and the method for inspection of RTP based on the life-span.The method is applicable to take polymeric materials such as high density polyethylene (HDPE), atactic copolymerized polypropene (PP-R) and heat-proof polythenes (PE-RT) as matrix, the RTP take steel wire, glass fibre, carbon fiber, aramid fiber and other Materials with High Strength etc. as reinforcing material.The serviceability temperature scope depends on heat-resisting (melting) temperature and low temperature resistant (embrittlement) temperature of matrix material in the RTP structure or adhesives, be that the RTP serviceability temperature scope that matrix does not contain adhering resin can be-20～100 ℃ for tygon, inside and outside medium is that water, sandstone, seawater or other contain the medium of microbial attack or chemical corrosion.

By method of the present invention, burst pressure in the time of can realizing by short-term test prediction and checking R TP pipe range under tenure of use, the hydrostatic strength measuring method need to be done a large amount of operations that hydrostatic test is tested when long when having avoided tradition based on extrapolation method long, saved the RTP production cost, shorten the production cycle, increased reliability and the product competitiveness of RTP.

Embodiment

Design and the method for inspection based on the reinforced thermoplastics complex pipe in life-span are implemented in accordance with the following steps:

1.RTP quick bursting test

RTP explosion bulge test method is with reference to GB/T 6111-2003 " fluid is carried with thermoplastic plastic pipe internal pressure-resistant test method ".The sealing at RTP two ends need be selected the A type end socket of stipulating among the GB/T 6111-2003.

Test temperature is set as the environment temperature T when RTP is actual to be used _aTest is carried out in air, the medium of medium available water or actual fed in the sample.The pressure controling precision of tubing is withstand voltage heat stabilization test machine is at least 1%.

RTP is suppressed until explosion needs the test findings of record to comprise: a) burst pressure; B) blasting time.

Behind the RTP Explosive Failure, that the reinforcing material fracture occurs be effective Explosive Failure result, and other come unstuck etc. such as end leakage, interface, and to lose efficacy be invalid test findings.If single test result's burst pressure or explosion required time and average differ more than 20%, then abandon this time test findings.Rationally regulate the flow of pressuring pump, so that blasting process time value is in more rational scope.Explosion bulge test is finished with the short as far as possible time between 30s to 1h.Simultaneously, should be noted following item in the process of the test: 1) the sample status adjustment time is with reference to GB/T 6111 regulations; 2) note control pressuring pump flow, make each blasting time differ as far as possible little; 3) to begin timing be the moment that begins to rise from the RTP overpressure blasting time, rather than suppress the moment of beginning; The end point of blasting time is that matrix material begins the moment that large deformation causes the RTP pipe pressure to begin to descend, rather than the moment of the complete fracturing fluid outflow of tubing.

Repeat this test until obtain at least 3 above valid data.Calculate as follows the average burst pressure P of many explosion bulge tests of RTP _bAnd corresponding average blasting time t _bIf the ratio of the standard deviation of arbitrary test findings and average surpasses 10%, then reject the larger test findings of deviation.If the efficiency test result is less than 3 behind the elimination test point, then re-start complementary testing.Need to prove that the valid data ratio more and standard deviation and average of counting is less, then the result of prediction is more for accurately.

$P_b=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{P}_{\mathrm{bi}}---\left(1\right)$

$t_b=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{t}_{\mathrm{bi}}---\left(2\right)$

In the formula, n is the efficiency test number as a result of RTP quick bursting test;

P _BiBe burst pressure, MPa;

t _BiBe blasting time, s;

i＝1，2，3......

2.RTP withstand voltage test

Suitably reduce test pressure and carry out the withstand voltage test of RTP.Withstand voltage test method is with reference to GB/T 6111-2003 " fluid is carried with thermoplastic plastic pipe internal pressure-resistant test method ".The sealing at RTP pipe two ends need be selected the A type end socket of stipulating among the GB/T 6111-2003.

Test temperature is set as the environment temperature T when RTP is actual to be used _aTest is carried out in air, the medium of medium available water or actual fed in the sample.The pressure controling precision of tubing is withstand voltage heat stabilization test machine is at least 1%.RTP is suppressed rapidly until then a certain set pressure keeps this pressure until the RTP explosion.After the RTP explosion, need the test findings of record to comprise: a) burst pressure; B) blasting time.

If blasting time outside 72～10000h, then is invalid test result; Fine setting reduces test pressure repeatedly, so that blasting time always in 72～10000h scope, is recorded each burst pressure P _iWith blasting time t _i

Repeat above-mentioned test until obtain effective result more than at least 3.

Obtain n efficiency test data point, calculate as follows average burst pressure P _n, logarithm blasting time average t _1nAnd logarithm square blasting time average t _2n:

$P_n=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{P}_i---\left(3\right)$

$t_{1n}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\lg \left({2t}_i\right)---\left(4\right)$

$t_{2n}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\lg }^2\left({2t}_i\right)---\left(5\right)$

In the formula, n is the efficiency test number as a result of RTP pipe withstand voltage test;

P _iBe burst pressure ,/MPa;

t _iBe blasting time ,/h;

i＝1，2，3......

3. reinforcing material tension test

The reinforcing material tension test is in order to obtain the breaking elongation of reinforcing material.

If reinforcing material is steel wire, such as the steel wire winding reinforced plastic pipe, then according to GB/T 228-2002 " metal material tensile test at room temperature " standard tensile until the fracture, record breaking elongation.

If reinforcing material is carbon fiber, then according to GB/T 3362-2005 " carbon fiber tensile property of multi-filament test method " standard tensile until the fracture, record breaking elongation.

If reinforcing material is glass fibre, then according to GB/T 1447-1983 " Test method for tensile properties of glass fiberreinforced plastics " standard tensile until the fracture, record breaking elongation.

If reinforcing material is other high-strength chemical fibers, then according to GB/T 19975-2005 " high-strength chemical-fibre filament draw method for testing performance " standard, record breaking elongation.

Should be noted protection end clamping part before the reinforcing material tension test, if fracture position within the zone of chuck clamping, then is considered as invalid test result.The process of the test environment temperature still is set as T _a, the conditions such as simultaneously attention maintenance ambient humidity satisfy the requirement of standard code, and it is identical to control each tensile strain rate (rather than pulling speed).Record the breaking elongation of each reinforcing material after the off-test.

Repeat above-mentioned process of the test, measure at least 3 above efficiency test results.Calculate the mean value ε of breaking elongation _fIf efficiency test result's number is n, then:

${\mathrm{\ϵ}}_f=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ϵ}}_{\mathrm{fi}}---\left(6\right)$

If the ratio of the standard deviation of arbitrary test findings and average surpasses 10%, then reject the larger test findings of deviation.If the efficiency test result is less than 3 behind the elimination test point, then re-start complementary testing.

4. matrix material tension test

The relaxation property of matrix material under specific strain and rate of strain measured in the tension test of matrix material.Test method reference standard GB/T 8804-2003 " thermoplastic plastic pipe tensile property mensuration-Di 3 part polyolefin pipes " carries out.

Test temperature is set as the environment temperature T when RTP is actual to be used _aThe tension test process is first with constant rate of strain

Be stretched to strain stress _g, record tensile force f at this moment _Gi, stop simultaneously stretching and keep tensilometer two ends clip position, keep 30min after, the tensile force f after the record matrix material is lax _JiRepeat above-mentioned process of the test, until obtain n above valid data, the value of n is according to table 1.

Table 1 matrix material tension test quantity of sampling quantity

Nominal outside diameter d n	15≤d n＜75	75≤d n＜280	280≤d n＜450	d n≥450
					The batten number	3	5	5	8

The calculating strain is ε _gThe time each tensile force f _gAnd each tensile force f after lax _jRatio h.If the ratio of the standard deviation of arbitrary test findings and average surpasses 10%, then reject the larger test findings of deviation.If the efficiency test result is less than n behind the elimination test point, then re-start complementary testing.Force rate before and after lax is:

$h=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\frac{F_g}{F_j}---\left(7\right)$

In the tension test process of above-mentioned matrix material, ε _gChoose as follows:

If a) reinforcing material of RTP be just anticlinal around steel wire or the material such as aramid fiber, then

${\mathrm{\ϵ}}_g=\frac{{\mathrm{\ϵ}}_f}{{\cos }^2\mathrm{\θ}}---(8-a)$

B) if the reinforcing material of RTP is composite bed, then

ε _g＝ε _f (8-b)

In the formula, θ is reinforcing material and winding angle perpendicular to the axis plane;

ε _fBreaking elongation for reinforcing material.

The rate of strain that matrix material stretches is calculated as follows:

In the formula, t _bBe the average blasting time of quick bursting test ,/s.

5. burst pressure prediction when long based on the RTP in life-span

If the life-span that requires the life-span of design maybe to need to check to use is x (unit: year), by following formula design factor:

$K=\frac{h-(B_1\·{\lg }^{2}x+B_2\·\mathrm{lgx}+B_3)}{h-(A_1\·t_{2n}+A_2\·t_{1n}+A_3)}---\left(10\right)$

The pressure that the RTP maximum that then requires serviceable life based on x can be born is:

P _life＝P _b-K·(P _b-P _n) (11)

If matrix material is high density polyethylene (such as PE80 or PE100), atactic copolymerized polypropene (PP-R) and heat-proof polythene (PE-RT), then the coefficient in the formula (10) is chosen by table 2.

Table 2 life-span design factor (* 10 ^-3)

	A 1	A 2	A 3	B 1	B 2	B 3
							HDPE or PE-RT	9.584	-163.4	995.4	9.584	-87.83	500.1
PP-R	8.158	-167.2	1000.0	8.158	-102.87	467.6

If the method is used for the product quality inspection of RTP, calculate according to above-mentioned 5 steps equally and dope the burst pressure of product under requiring tenure of use, judge by the relation of this burst pressure and design pressure relatively whether product is qualified.If P _Life〉=K ' P _Design, judge that then product is qualified; Wherein K ' is for according to reinforcing material and the definite safety coefficient of use occasion.For the RTP take high-strength steel as reinforcing material, K is taken as between 1.75～3.0.For example: for frequent through traffic, underground installation is more or the zone of building more than 4 layers is arranged on the ground, K desirable 3.0; To the zones such as manufacturing district or residential district, suburbs, safety coefficient K desirable 2.5; For meagrely-populated zone, safety coefficient K desirable 1.75.

Embodiment 1:

Take steel wire winding reinforced plastic pipe (be called for short PSP) as example, the method for addressing with this patent predicts that PSP is the burst pressure in 50 years designed life.The PSP specification is as shown in table 3:

Table 3PSP specification

Nominal diameter/mm	Steel wire diameter/mm	The total radical of steel wire	Wall thickness/mm	Winding angle θ/°
					110	0.8	36	8.5	35.3

1, PSP quick bursting test

Test temperature T _aBe 20 ℃, medium is water in the sample, and the quick bursting test findings is as shown in table 4.

The relation of table 4 quick bursting pressure and blasting time

	Test 1	Test 2	Test 3
				Burst pressure/MPa	6.4	6.6	6.2
Blasting time/s	135	122	129

According to experimental result, the mean value of burst pressure is:

$P_b=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{P}_{\mathrm{bi}}=\frac{(6.4+6.6+6.2)}{3}=6.4\mathrm{MPa}$

The average blasting time of 3 separate explosions test is:

$t_b=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{t}_{\mathrm{bi}}=\frac{(135+122+129)}{3}=129s$

2, PSP withstand voltage test

PSP blasting time is as shown in table 5 in 72～10000h withstand voltage test result.

The relation of table 5 withstand voltage test burst pressure and blasting time

	Test 1	Test 2	Test 3
				Burst pressure/MPa	4.4	4.2	3.8
Blasting time/h	96	149	322

The average burst pressure of withstand voltage test is:

$P_n=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{P}_i=\frac{(4.4+4.2+3.8)}{3}=4.1\mathrm{MPa}$

The logarithm blasting time average of 3 withstand voltage tests is:

$t_{1n}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\lg \left({2t}_i\right)=\frac{\lg \left(192\right)+\lg \left(298\right)+\lg \left(644\right)}{3}=2.52h$

The logarithm of 3 withstand voltage tests square blasting time average is:

$t_{2n}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\lg }^2\left({2t}_i\right)=\frac{{\lg }^2\left(192\right)+{\lg }^2\left(298\right)+{\lg }^2\left(644\right)}{3}=6.41h$

3, steel wire tension test

The reinforcing material of PSP is steel wire, and its stretch test result is as shown in table 6.

Table 6 steel wire fracture length growth rate

The average elongation at break of steel wire is:

${\mathrm{\ϵ}}_f=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ϵ}}_{\mathrm{fi}}=\frac{(8.66\%+8.81\%+8.77\%)}{3}=8.75\%$

4, PE100 tension test

The matrix material of PSP is the YEM4803T that raises sub-petrochemical industry, is stretched to first strain during tension test

Its drawing process is with constant rate of strain

Carry out the tensile force f of record PE100 this moment _GiAs shown in table 7:

Table 7 PE100 tensile force f _Gi

	Test 1	Test 2	Test 3	Test 4	Test 5
						Tensile force f gi/KN	0.615	0.621	0.632	0.642	0.628

Stop simultaneously stretching and keep tensilometer two ends clip position, keep 30min after, the tensile force f after record PE100 is lax _JiAs shown in table 8:

Table 8 PE100 tensile force f _Ji

	Test 1	Test 2	Test 3	Test 4	Test 5
						Tensile force f ji/KN	0.385	0.381	0.388	0.407	0.395

Then the force rate of lax front and back is:

$h=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\left(\frac{F_{\mathrm{gi}}}{F_{\mathrm{ji}}}\right)=\frac{1}{5}\×(\frac{0.615}{0.385}+\frac{0.621}{0.381}+\frac{0.632}{0.388}+\frac{0.642}{0.407}+\frac{0.628}{0.395})=1.6$

5, the PSP of 50 year designed life prediction burst pressure

According to formula (10), design factor K

$K=\frac{h-(B_1\·{\lg }^{2}x+B_2\·\mathrm{lgx}+B_3)}{h-(A_1\·t_{2n}+A_2\·t_{1n}+A_3)}$

$=\frac{1.6-(9.584\×{10}^{-3}\×{\lg }^{2}50-87.83\×{10}^{-3}\×\lg 50+500.1\×{10}^{-3})}{1.6-(9.584\×{10}^{-3}\×6.41-163.4\×{10}^{-3}\×2.52+995.4\×{10}^{-3})}=1.28$

Then this PSP based on the PSP burst pressure of 50 year designed life is:

P _life＝P _b-K·(P _b-P _n)＝6.4-1.28×(6.4-4.1)＝3.5MPa

If the design pressure of the PSP of the described specification of 6 tables 1 tentatively is defined as 1.0MPa by producer, design service life is 50 years, need to carry out quality inspection to product with the method that this patent is addressed.

Predicted that by above-mentioned steps obtaining this PSP is 3.5MPa based on the design pressure in 50 year serviceable life, greater than design pressure.Because different use occasions, the user is different to the reliability requirement of product, the safety coefficient K of therefore selecting ' also not identical.Get safety coefficient K ' be 2.5, because

P _life＝3.5MPa≥2.5P _design＝2.5MPa

Therefore, the method that adopts this patent to address is qualified to the assay of this PSP.

Embodiment 2:

Take aramid fiber reinforced composite pipe (be called for short AFRP) as example, the method for addressing with this patent is predicted the burst pressure of AFRP 50 year designed life.The AFRP specification is as shown in table 9:

Table 9 AFRP specification

1, AFRP quick bursting test

Test temperature T _aBe 20 ℃, medium is water in the sample, and AFRP quick bursting test findings is as shown in table 10.

The relation of table 10 quick bursting pressure and blasting time

	Test 1	Test 2	Test 3
				Burst pressure/MPa	12.1	11.7	12.2
Blasting time/s	61	63	55

According to experimental result, the mean value of burst pressure is:

$P_b=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{P}_{\mathrm{bi}}=\frac{12.1+11.7+12.2}{2}=12.0\mathrm{MPa}$

The average blasting time of 3 separate explosions test is:

$t_b=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{t}_{\mathrm{bi}}=\frac{61+63+55}{3}=60s$

2, AFRP withstand voltage test

AFRP blasting time is as shown in table 11 in 72～10000h withstand voltage test result.

The relation of table 11 withstand voltage test burst pressure and blasting time

	Test 1	Test 2	Test 3
				Burst pressure/MPa	8.6	7.9	7.2
Blasting time/h	98	202	298

The average burst pressure of withstand voltage test is:

$P_n=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{P}_i=\frac{(8.6+7.9+7.2)}{3}=7.9\mathrm{MPa}$

The logarithm blasting time average of 3 withstand voltage tests is:

$t_{1n}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\lg \left({2t}_i\right)=\frac{\lg \left(196\right)+1g\left(404\right)+\lg \left(596\right)}{3}=2.56h$

The logarithm of 3 withstand voltage tests square blasting time average is:

$t_{2n}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\lg }^2\left({2t}_i\right)=\frac{{\lg }^2\left(196\right)+{\lg }^2\left(404\right)+{\lg }^2\left(596\right)}{3}=6.59h$

3, aramid fiber tension test

The reinforcing material of AFRP is aramid fiber, and its stretch test result is as shown in table 12.

Table 12 aramid fiber breaking elongation

The average elongation at break of aramid fiber is:

${\mathrm{\ϵ}}_f=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ϵ}}_{\mathrm{fi}}=\frac{1}{3}\×(1.98\%+2.03\%+1.89\%)=1.97\%$

4, PE100 tension test

The matrix material of AFRP is PE100, is stretched to first strain during tension test

Its drawing process is with constant rate of strain

Carry out the tensile force f of record PE100 this moment _GiAs shown in table 13:

Table 13 PE100 tensile force f _Gi

	Test 1	Test 2	Test 3	Test 4	Test 5
						Tensile force f gi/KN	0.209	0.213	0.205	0.215	0.207

Stop simultaneously stretching and keep tensilometer two ends clip position, keep 30min after, the tensile force f after record PE100 is lax _JiAs shown in table 14:

Table 14 PE100 tensile force f _Ji

	Test 1	Test 2	Test 3	Test 4	Test 5
						Tensile force f ji/KN	0.171	0.174	0.167	0.179	0.169

Then the force rate of lax front and back is:

$h=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\left(\frac{F_{\mathrm{gi}}}{F_{\mathrm{ji}}}\right)=\frac{1}{5}\×(\frac{0.209}{0.171}+\frac{0.213}{0.174}+\frac{0.205}{0.167}+\frac{0.215}{0.179}+\frac{0.207}{0.169})=1.22$

5, based on 50 years burst pressures of the AFRP in life-span

According to formula (10), design factor K

$K=\frac{h-(B_1\·{\lg }^{2}x+B_2\·\mathrm{lgx}+B_3)}{h-(A_1\·t_{2n}+A_2\·t_{1n}+A_3)}$

$=\frac{1.22-(9.584\×{10}^{-3}\×{\lg }^{2}50-87.83\×{10}^{-3}\×\lg 50+500.1\×{10}^{-3})}{1.22-(9.584\×{10}^{-3}\×6.59-163.4\×{10}^{-3}\×2.56+995.4\×{10}^{-3})}=1.45$

Then based on the AFRP burst pressure that requires 50 year designed life be:

P _life＝P _b-K·(P _b-P _n)＝12.0-1.45×(12.0-7.9)＝6.1MPa。

Burst pressure P when 6, long _LifeWith design pressure P _DesignRelation, if the AFRP design pressure of this specification is 2.0MPa, safety coefficient K ' be 2.5 because

P _life＝6.1MPa≥2.5P _design＝5.0MPa

Therefore, the method that adopts this patent to address is qualified to the assay of this AFRP.

Claims (3)

1. based on the method for inspection of the reinforced thermoplastics complex pipe of designed life, may further comprise the steps:

(1) RTP explosion bulge test: by the quick bursting test, measure the average burst pressure P of RTP _bAnd corresponding average blasting time t _b

Described

In the formula, n is the efficiency test number as a result of RTP quick bursting test; t _BiBe blasting time, s; I=1,2,3

(2) RTP withstand voltage test: RTP is suppressed rapidly to a certain set pressure, then keep this pressure until the RTP explosion is adjusted set pressure to control pressure-resistant time at 72 ~ 10000 hours; Measure average burst pressure P _n, logarithm blasting time average t _1nAnd logarithm square blasting time average t _2n

Described logarithm blasting time average t _1nAnd logarithm square blasting time average t _2nObtain according to following formula:

In the formula, n is the efficiency test number as a result of RTP pipe withstand voltage test; t _iBe blasting time, h; I=1,2,3

(3) reinforcing material of RTP carried out tension test, measure the mean value ε of its breaking elongation _f

(4) matrix material of RTP is carried out tension test, first with constant rate of strain

Be stretched to strain stress _gAfter, keep again 30min, measure matrix material at the force rate h of lax front and back;

Described ε _gChoose as follows:

(a) if the reinforcing material of RTP be just anticlinal around steel wire or aramid fiber material, then

(b) if the reinforcing material of RTP is composite bed, then

ε _g＝ε _f （8-b）

In the formula, θ is reinforcing material and winding angle perpendicular to the axis plane;

The rate of strain that described matrix material stretches

Calculate as follows:

Burst pressure P when (5) long based on the RTP of designed life _LifeFor:

P _life＝P _b-K(P _b-P _n)；

In the formula, x is the serviceable life of designing requirement, unit: year;

Described A ₁, A ₂, A ₃, B ₁, B ₂, B ₃Be according to the matrix material material and definite coefficient * 10 ^-3, determine according to following table:

A ₁ A ₂ A ₃ B ₁ B ₂ B ₃ HDPE or PE-RT 9.584 -163.4 995.4 9.584 -87.83 500.1 PP-R 8.158 -167.2 1000.0 8.158 -102.87 467.6

Burst pressure P when (6) long _LifeWith design pressure P _DesignRelation, if P _Life〉=K ' P _Design, judge that then product is qualified; Wherein K ' is the safety coefficient definite according to use occasion.

2. the method for inspection according to claim 1 is characterized in that, in RTP explosion bulge test and RTP withstand voltage test, test temperature is set as the environment temperature T when RTP is actual to be used _a, test is carried out in air, and the medium in the sample is water or actual fed medium.

3. the method for inspection according to claim 1 is characterized in that, in the tension test to RTP reinforcing material and matrix material, test temperature is set as the environment temperature T when RTP is actual to be used _a