SU1211620A1 - Method of hydrostatic testing of pipelines for strength and pressure tightness - Google Patents

Abstract

The invention relates to a control and measurement technique and can be used ano in the construction of pipelines (T) for the transport of liquid and gaseous substances. The purpose of the invention is to increase the reliability and productivity of testing T when laying them in frozen soils due to the optimal choice of the desired thickness of the aureole of the thawed soil (TO OG) and the circulation time of the heat carrier (TH). For the period of preparation, T is filled with TH and is circulated through T at a positive temperature until the necessary OH exhaust gas S is formed around T. Then, for the tests, T is filled with water, and the volatilization is then TH. The pressure is raised to T and strength tests are carried out. After that, the pressure is reduced to the operating level and leak tests are performed. At the end of the test, the water is removed. The OH and the circulating time are determined by the formulas S Ад Adl Э «1 Q Га Haa + Sm, p / 1-8. , -g where r en (ui-), m. IQf are the thermal conductivity coefficients of frozen and thawed ground, kcal-m.h.grad; t, trp - temperature of TH and frozen ground. WITH; - the time of all subsequent circulating TH operations, hours; g - outer radius T, m; volumetric heat capacity of frozen soil, kcal / m hail; the heat of phase transformations of water in the soil, kcal / m is hidden; weight of soil moisture, unit fraction; Y is the volume mass of the soil, kg / m. 3 pe. (L ced o w o w

Description

I 1

The invention relates to instrumentation engineering and can be used to test pipelines for transporting gas, oil, petroleum products, and the like. when laid in soils with a negative temperature, in particular in permafrost areas.

The aim of the invention is to increase the reliability and performance of the tests, due to the optimal choice of the required thickness of the aureole of the soil and the circulation time of the coolant. „

FIG. Figure 1 shows a plot of pressure P over time C; in fig. 2 is a graph of the temperature change of the pipeline t; in fig. 3 is a plot of thickness changes in slush soil around the pipeline.

The numbers in FIG. 1, various operations of the testing process are indicated.

The method of hydraulic testing of pipelines for durability and pressure tightness includes preparation, during which the pipeline is filled with coolant (0-1) and the coolant circulates through the pipeline (1-2), the pipeline is filled with water (2-3) with displacement this heat carrier, pressure rise (3-4), pressure hold (4-7), during which strength tests are performed at elevated pressure (4-5), pressure drop to working (5-6), leak test under working pressure (6-7) and removal water (7-8). During filling of the pipeline with coolant and circulation of the coolant through the pipeline (time), the soil thaws around the pipeline to the thickness of halo 2 when the coolant circulates. In the case of thermal inertia, thawing occurs some time after the end of the circulation of the coolant and the thickness of the thawed halo reaches 8 ° a. Then the thickness of the halo S begins to decrease, and by the time the water is removed from the pipeline, the og decreases to Jj. This value should be positive to prevent water from freezing on the walls of the pipeline. On the other hand, too large a Sg value means that the heat carrier is circulating 116ZO2

The bodies were carried out too long, this increases the testing time and, consequently, reduces their productivity. The thickness of the halo from the bottom of the ground, necessary for further operations at a positive temperature of the pipeline and the circulation time of the coolant necessary to create a halo of 10 of this thickness, is determined by the formulas:

(V kj

 i-q

/ irp /

g / e

15

20

35

(QQ C / trp / -S (S4-r) S-A.-t

()

25

thirty

where o is the thickness of the halo

soil, m;

. thermal conductivity coefficient of the soil in the frozen and thawed state, respectively, kcal / m.h.grad; heat carrier temperature

and frozen soil, respectively, ° C;

o is the time for all subsequent circulating coolant operations, h; g - outer radius of pipelines, m;

Sd, - volumetric heat capacity of frozen soil, kcal / m hail; QQ - latent phase heat

transformations of water in the soil, kcal / m;

About SOJiL Q 1 + W

(3)

40 where W is the weight moisture of the soil,

unit shares; Y is the volume mass of the soil, kg / m.

Example. Consider testing a pipeline section with a diameter of 529 mm (, 2645 m) in frozen ground with a temperature C. The time required for all operations that follow the circulating coolant, taking into account possible repair of defective places, will take Rs 72 h. - Ground parameters: –y 1700 kg / m; , 3; Cap / m hail; , 3 kcal / mh hail; AT I, I kcal / m.ch. hail; p - 31385 kcal / m. Substituting the values of the parameters in formulas (1) and (3), we obtain the necessary hypotheses for the aureole of the melted bluff S 0.17 m.

The time, required to create such a halo thickness, is determined from formula (2). So, at the temperature of the coolant C 10 h, and at C 41 h.

Claims (1)

Formula inveni.ni The method of hydraulic testing of the pipeline for strength and leaktightness under negative ground temperature conditions, including preparation, during which the coolant circulates through the pipeline at a positive temperature for a period of time to allow the formation of a halo around the pipeline with a thickness sufficient to further operations at a positive temperature of the pipeline walls, filling the pipeline with water, raising the pressure, holding the pressure m and removal of water, characterized in that, with In order to increase the reliability and performance of the tests due to the optimal choice of the required thickness of the aureole of the thawed soil and the circulation time of the coolant, these values are calculated using the formulas / 7 "Vw from H am / trpltj 2 8H- + P.-T;  "but (, / t, p / l. (Sfrl, g En ( four), where in t, t, p - thickness, halo otta our soil, m;  the thermal conductivity of the soil in the frozen and thawed state, respectively, kcal / m.h. hail; temperature of the coolant and frozen soil, respectively, ° Cj 3 the time of all the subsequent circulating coolant operations, h; g - the outer radius of the pipeline, m;  - volumetric heat capacity of frozen soil, kcal / m hail; Rl hidden phase heat transformations of water in the soil, kcal / m; 80 Wy I + W weight of soil moisture, unit fraction; bulk soil mass, kg / m. Q where w phew {/ 9 .2