CN104266961B - The hot oxygen accelerated aging tester of in-service polyethylene pipe and life-span prediction method - Google Patents

Abstract

The hot oxygen accelerated aging tester of a kind of in-service polyethylene pipe and life-span prediction method belong to polyethylene pipe life tests technical field.Air pump, valve, Pressure gauge, air relief valve and polyethylene pipe are sequentially connected with by pipeline liquid injecting device；Polyethylene pipe is closed by sealing clamp；Polyethylene pipe is placed in ageing oven.By carrying out hot oxygen accelerated aging test with the new polyethylene pipeline of the trade mark and size in the temperature conditions of 100 DEG C and 110 DEG C to the in-service polyethylene pipe temperature conditions in 110 DEG C and with in-service polyethylene pipe, make it that brittle break to occur respectively, record three tests institute through time t_{Old 110}、t_{New 100}、t_{New 110}, obtain the bimetry t of in-service polyethylene pipe_real:Hot oxygen accelerated aging tester can carry out thermo-oxidative ageing test under the internal pressure conditions that polyethylene pipe keeps identical with actual condition, and device is simple, and test period is short；Use the method that the life-span of in-service polyethylene pipe is predicted by this assay device, it is possible to using for engineering provides theoretical reference.

Description

The hot oxygen accelerated aging tester of in-service polyethylene pipe and life-span prediction method

Technical field

The invention belongs to polyethylene pipe life tests technical field, particularly to hot oxygen accelerated aging tester and the life-span prediction method of a kind of in-service polyethylene pipe.

Background technology

Polyethylene pipe has good physical and mechanical properties, decay resistance and superior economy, replaces traditional metallic conduit gradually, obtains general application on fuel gas transmission.But polyethylene belongs to macromolecular material, it is easy to occur aging, the problem that therefore polyethylene pipe exists ageing failure.Polyethylene pipe under certain pressure effect, its service life is a very most important index in engineer applied, experiments show that the service life of high-density polytene pipeline was up to more than 50 years.At present, it is the ISO9080 standard (measuring the long-term working fluid static strength of thermoplastic tube shaped material by deduction method) adopting America Plastic pipeline association to formulate to the life prediction formula of polyethylene tube, as shown in Equation 1:

${\log t}_f=[A+\frac{B}{T}]+[C+\frac{D}{T}]{\log \mathrm{\σ}}_{\mathrm{\θ}}---\left(1\right)$

In formula: t_fBurn-out life, h；T hydrostatic test temperature, DEG C；The Parameters in Regression Model that A, B, C, D are relevant with concrete material trademark；σ_θCircumference stress when suppressing.This test period is long, low temperature hydrostatic test often some months, the even several years, and needs hydrostatic test instrument, and instrument requirements is high.

But, due to the impact of the factor such as construction quality, damage from third-party so that the service life of polyethylene pipe system is greatly shortened.Once there is the blast of a lot of polyvinyl fuel gas pipeline and leakage accident both at home and abroad, and caused serious economic loss, even endanger personal safety.Visible, it is ensured that the safe operation of polyvinyl fuel gas pipeline system, the necessary actual life to polyethylene pressure pipe road is studied.

Summary of the invention

The invention provides the hot oxygen accelerated aging tester of a kind of in-service polyethylene pipe and life-span prediction method, by carrying out the hot oxygen accelerated aging test of polyethylene pipe under pressure-bearing, it was predicted that the burn-out life of in-service polyethylene pipe.

The technical scheme that the hot oxygen accelerated aging tester of in-service polyethylene pipe of the present invention adopts is:

Air pump, valve, Pressure gauge, air relief valve and polyethylene pipe are sequentially connected with by pipeline liquid injecting device；Polyethylene pipe is closed by sealing clamp, makes to be formed in polyethylene pipe airtight cavity；Polyethylene pipe is placed in ageing oven.

Between described ageing oven and pipeline liquid injecting device, sealing ring is set.

The life-span prediction method of in-service polyethylene pipe provided by the invention, sequentially includes the following steps:

(1) in hot oxygen accelerated aging tester, when in 100 DEG C with the temperature conditions of 110 DEG C and the overpressure consistent with actual condition, hot oxygen accelerated aging test is carried out respectively to the new polyethylene pipeline of the same trade mark of in-service polyethylene pipe and size, until new polyethylene pipeline generation brittle break, record twice test institute through the time, be designated as t respectively_{New 100}、t_{New 110}；

(2) in hot oxygen accelerated aging tester, in the temperature conditions of 110 DEG C and the overpressure consistent with actual condition when, in-service polyethylene pipe is carried out hot oxygen accelerated aging test, until in-service polyethylene pipe generation brittle break, record test institute through the time, be designated as t_{Old 110}；

(3) activation energy according to same polyvinyl piping materials is equal, obtains following formula:

Wherein: t_realIt is the in-service polyethylene pipe out-of-service time under actual condition, T₁₀₀、T₁₁₀And T_realIt is the actual condition temperature of 100 DEG C, 110 DEG C and in-service polyethylene pipe respectively；

(4) by the conversion of step (3), in-service polyethylene pipe bimetry t under actual condition is obtained_real:

The invention have the benefit that

Described hot oxygen accelerated aging tester can carry out thermo-oxidative ageing test under the internal pressure conditions that polyethylene pipe keeps identical with actual condition, and device is simple, and test period is shorter, and each degradation all can complete in one day；Meanwhile, the invention provides the method using this assay device that the life-span of in-service polyethylene pipe is predicted, it is possible to using for engineering provides theoretical reference.

Accompanying drawing explanation

Fig. 1 is the structural representation of device of the present invention.

Number in the figure:

1-air pump；2-valve；3-Pressure gauge；4-air relief valve；5-polyethylene pipe；6-sealing clamp；7-ageing oven；8-sealing ring.

Detailed description of the invention

The invention provides the hot oxygen accelerated aging tester of a kind of in-service polyethylene pipe and life-span prediction method, below in conjunction with the drawings and specific embodiments, the present invention will be further described.

Hot oxygen accelerated aging tester provided by the invention is as it is shown in figure 1, be made up of for pressure device and heater gas: described gas is combined by air pump 1, valve 2, Pressure gauge 3, air relief valve 4, polyethylene pipe 5 and sealing clamp 6 for pressure device；Air pump 1 provides source of the gas, is connected with valve 2 by pipeline liquid injecting device, and valve 2 is connected with Pressure gauge 3 by pipeline liquid injecting device, and Pressure gauge 3 is connected with air relief valve 4 by pipeline liquid injecting device；Air relief valve 4 is connected with polyethylene pipe 5 by pipeline liquid injecting device, and polyethylene pipe 5 right-hand member carries out end seals process by sealing clamp 6.Air relief valve 4 is used for preventing pressure-bearing polyethylene pipe overpressure in ageing oven heating process from raising, and ensures consistent with actual condition pressure on the one hand, ensures testing crew safety on the other hand.Described heater includes ageing oven 7 and sealing ring 8, and gas is sealed by sealing ring 8 between pressure device and ageing oven 7, it is to avoid heat losses in ageing oven 7, causes that heating-up temperature reduces.

Use this assay device that in-service polyethylene pipe is carried out biometry, sequentially include the following steps:

(1) in hot oxygen accelerated aging tester, when in 100 DEG C with the temperature conditions of 110 DEG C and the overpressure consistent with actual condition, hot oxygen accelerated aging test is carried out respectively to the new polyethylene pipeline of the same trade mark of in-service polyethylene pipe and size, until new polyethylene pipeline generation brittle break, record twice test institute through the time, be designated as t respectively_{New 100}、t_{New 110}；

(2) in hot oxygen accelerated aging tester, in the temperature conditions of 110 DEG C and the overpressure consistent with actual condition when, in-service polyethylene pipe is carried out hot oxygen accelerated aging test, until in-service polyethylene pipe generation brittle break, record test institute through the time, be designated as t_{Old 110}；

(3) activation energy according to same polyvinyl piping materials is equal, obtains following formula:

Wherein: t_realIt is the in-service polyethylene pipe out-of-service time under actual condition, T₁₀₀、T₁₁₀And T_realIt is the actual condition temperature of 100 DEG C, 110 DEG C and in-service polyethylene pipe respectively；

(4) by the conversion of step (3), in-service polyethylene pipe bimetry t under actual condition is obtained_real:

When carrying out degradation, it is first turned on valve 2 every time, the value of air relief valve 4 is set, open air pump 1, gas is carried out pressurising for pressure device, treat that the reading of Pressure gauge 3 meets requirement of actual working condition stable closedown valve 2 afterwards, open ageing oven 7, carry out temperature setting and start experiment.

The above; it is only the present invention preferably detailed description of the invention; but protection scope of the present invention is not limited thereto; any those familiar with the art is in the technical scope that the embodiment of the present invention discloses; the change that can readily occur in or replacement, all should be encompassed within protection scope of the present invention.

Claims (2)

1. the hot oxygen accelerated life Forecasting Methodology of an in-service polyethylene pipe, assay device is, air pump (1), valve (2), Pressure gauge (3), air relief valve (4) and polyethylene pipe (5) are sequentially connected with by pipeline liquid injecting device；Polyethylene pipe (5) is closed by sealing clamp (6), makes to be formed in polyethylene pipe (5) airtight cavity；Polyethylene pipe (5) is placed in ageing oven (7), it is characterised in that the method sequentially includes the following steps:

(1) in hot oxygen accelerated aging tester, when in 100 DEG C with the temperature conditions of 110 DEG C and the overpressure consistent with actual condition, hot oxygen accelerated aging test is carried out respectively to the new polyethylene pipeline of the same trade mark of in-service polyethylene pipe and size, until new polyethylene pipeline generation brittle break, record twice test institute through the time, be designated as t respectively_{New 100}、t_{New 110}；

(2) in hot oxygen accelerated aging tester, in the temperature conditions of 110 DEG C and the overpressure consistent with actual condition when, in-service polyethylene pipe is carried out hot oxygen accelerated aging test, until in-service polyethylene pipe generation brittle break, record test institute through the time, be designated as t_{Old 110}；

(3) activation energy according to same polyvinyl piping materials is equal, obtains following formula:

Wherein: t_realIt is the in-service polyethylene pipe out-of-service time under actual condition, T₁₀₀、T₁₁₀And T_realIt is the actual condition temperature of 100 DEG C, 110 DEG C and in-service polyethylene pipe respectively；

(4) by the conversion of step (3), in-service polyethylene pipe bimetry t under actual condition is obtained_real:

2. the hot oxygen accelerated life Forecasting Methodology of in-service polyethylene pipe according to claim 1, it is characterised in that sealing ring (8) is set between described ageing oven (7) and pipeline liquid injecting device.