Construction of oil pipeline on type II swamp-Ludnikova

Contents

p

Introduction

Source Data

Design part

Select Insulation Type and Design

Selection of cargo type and grade

Determination of cargo placement step

Defining Trench Parameters

Process Part

Define how to lay

Preparatory work

Earthworks

Welding and installation works

Insulation and cleaning works

Stacking works

Fixing at design elevations

Strength and tightness tests

Quality control of works

Statement of requirements for mechanisms

Scope Sheet

Routing

Bibliographic list

Introduction

Pipeline transport of gas, oil and petroleum products is currently the main means of delivering these products from production, processing to consumption places. The main oil and gas fields in Russia are located in the eastern and northeastern regions. Pipelines with a length of 2000-3000 km are being built to transport oil and gas to the central and western regions. Pipelines of this length cross a huge number of various obstacles: small and large rivers, reservoirs, lakes, deep swamps stacked with weak soils, mountains, deserts, various crossings through railway and a/d roads.

There is an unusually wide range of various kinds of adverse effects on pipelines depending on the type of obstacles crossed. All these effects are only an addition to the main load - internal pressure reaching 54-75 kgf/cm2.

In practice, when designing and building crossings, the task of creating pipelines that could work without accidents and repairs for 40-50 years should be solved.

This course project is dedicated to the issue of creating a pipeline under the conditions of laying it in such a difficult place as a type II swamp.

The section of the oil pipeline considered in our course project with a length of 749.8 m on the Ukhta-Yaroslavl highway is a transition through a type II swamp with a convex relief (judging by the natural elevation of the ground). The oil pipeline was laid parallel to the terrain at a depth of 1.6 meters from the ground surface (design elevations of the bottom of the pipe). The maximum height difference is 0.6 m.

Throughout the area under consideration, a layer of decomposed peat (< 30%) with a capacity of 1 m lies on the earth's surface. At a depth of 1 m, there is a layer of water parallel to the terrain. Under the peat is a layer of fine sand with a capacity of 2 m.

Source Data

L = 749.8 m - length of the project section;

pumped product - oil;

Dn = 820 mm - external diameter of the pipeline;

δ = 11.4 mm - pipe wall thickness;

Prab = 5.4 MPa;

Specification 143127084 - GOST for pipes:

Rn1 = 510 MPa; Rn2 = 353 MPa;

steel brand - 17G1S; K52;

Rzav = 9.1 MPa - factory test pressure;

Period of works execution - winter;

Straight-joint welded pipes made of normalized low-alloy steel;

Material reliability factor K1 = 1.47.

Task: design oil pipeline through type II swamp.

Design part

Select Insulation Type and Design

As per item 10.4. [1, p. 38] a reinforced type of corrosion protection coating of pipelines is used for the marshy area. We assume that the temperature of the pumped product does not exceed 40 ° C.

According to [5, p. 241], reinforced insulation is selected for the trace and base conditions based on the bitumen-rubber mastic of the following construction:

- primer;

- 6 mm thick bitumen-rubber mastic (2 layers of 3 mm each);

- brizol.

The total insulation thickness will be 7.5 mm.

For primer material, we select bitumen of BN-IV grade by mixing it with gasoline with octane number 6676, GOST 208467 in a ratio of 1:3 in volume [5, p. 252].

Bitumen of BNI - IV grade (GOST 981261) [5, p. 242] is used for preparation of bitumen-rubber mastic.

For the preparation of rubber crumbs, we use the material "Chloroprene rubber" [5, p. 243], which has chemical resistance against oils, oxygen, ozone, is not prone to aging.

As a protective material, we select high-strength Br-II grade brizole (GOST 1717671) [5, p. 245].

As a plasticizer (to increase the plasticity of insulating mastics at negative temperatures), green oil is used.

Process Part

Define how to lay

According to [1, page 23], the laying of pipelines on swamps should be provided, as a rule, in a straight line with a minimum number of turns.

According to recommendation [8, p. 331], as well as [8, p. 315] in winter for type I and II marshes, laying must be carried out from a temporary technological road (winter road) laid along the trench.

2.2. Preparatory work

The width of the land strip for temporary use for the construction period for one main underground pipeline D = 820 mm is 28 m [7, p. 126].

It is necessary to create a geodetic breakdown basis for construction and at least 10 days before the start of construction and installation work to transfer to the contractor technical documentation for it and for points and signs fixed on the pipeline construction route, including:

- door signs of route turning angles in the amount of at least two for each angle direction within visibility;

- door signs on straight sections of the route, installed in pairs within visibility;

- high-altitude benchmarks;

- explanatory note, abrists of signs arrangement and their drawings;

- catalogs of coordinates and elevations of geodetic base points.

Permissible mean - quadratic errors when constructing a geodetic breakdown base:

- angular measurements ± 2 ′;

- linear measurements 1/1000;

- determination of elevations ± 50 mm.

Before starting construction, the general contractor construction and installation organization must perform the following works on the route:

- check the geodetic basis;

- install additional signs (milestones, pillars, etc.) along the axis of the route and along the boundaries of the construction strip;

- take out the horizontal curves of natural (elastic) bending in 10 m, and artificial bending in 2 m.

- break the picket along the entire alignment and at its characteristic points (at the beginning, middle and end of the curves).

Slats of broken points shall be fixed by signs, as a rule, outside the area of construction and installation works.

Prior to the start of the main construction and installation works, the general contractor shall, if necessary, in addition to the requirements of Chapters 2 and 3 of SNiP 3.01.0185 * "Organization of Construction Production," perform, taking into account specific construction conditions, the following preparatory work on the route:

- clear the pipeline outlet from the forest, shrubs, stumps and

boulders;

- implement measures ensuring minimum freezing

soil in the trench strip for the pipeline;

- build temporary technological roads (winter);

- arrange temporary acquisition and station bases or warehouses for storage of materials and equipment;

- prepare temporary production bases and sites for welding, tar-smelting and other works;

- create temporary villages providing the necessary housing, sanitary conditions for workers;

- prepare helipads (if necessary);

- create a dispatch communication system; [2, c.12]

Clearance of the route for the construction period shall be carried out within the limits of the diversion lane established by the project.

In winter, clearance should be carried out in two stages: in the area of ​ ​ passage of transport and the work of construction machines - in advance of the start of the main work, and in the area of ​ ​ digging the trench - immediately before the work of earth-moving machines for the length that ensures their operation during the shift.

The road strip is cleared from swamp vegetation by bush cutters of DP - 4 brand (2 pieces).

Stumps according to [8, p. 57] in type II swamps in winter are not made. Fine-sized trees with a diameter of up to 20 cm are bulldozed.

Clearance of the route is carried out by special timber crews of 5-6 people [7, p. 153]. The brigade is equipped with a Kamatsu D-355A bulldozer (2) and a TDT-75 (2) track tractor. To roll trees and sawn bitches from trees, benzomotor saws "Druzhba - 4 A" (3) are used. Trees must be sawn at ground level.

A paved road shall be laid at a distance of 0.5 m from the upper edge of the trench with a carriageway width of 6.5 m [8, p. 65].

We arrange a temporary technological road for the passage of construction and transport vehicles with a single-lane widening in places of turns, turns and junctions (from the pipeline side opposite the cable communication line route). We arrange trips at a line of sight, but no more than 600 m later. During the construction of the winter road, we limit ourselves to compacting the snow cover with freezing of the ice crust, freezing of the ground surface and maintaining the roadway in good condition [2, page 9].

2.3. Earthworks

Trench parameters during digging shall correspond to those calculated in item 1.4. of this project:

- trench width along bottom B = 1.76 m;

- trench depth ht = 1.6 m

- slope of trench slopes m = 1:1;

- trench width along the top B1 = 4.96 m.

Development of the trench is carried out by a single bucket excavator with a reverse shovel on widened caterpillars [2, p. 10]. For work, we use the ICC-72 excavator, which has a turning part from the EO-4121 excavator and a special caterpillar track (with wide caterpillars) [8, p. 416].

First, peat is torn apart (with a capacity of 1 m) and loaded to the other side of the trench in a dump. Then a layer of mineral soil with a thickness of 0.8 meters is removed (thus deepening the trench 20 cm below the design elevations [7, p. 193]) and piled into the dump next to the peat dump, but from the side closest to the trench.

Stacking works

We carry out the production of insulation laying works in a combined way using pipe layouts equipped with TP 822 CL (5) trolley suspensions. Soft towels shall be used to maintain the insulated piping (behind the insulation machine). Sharp jerks in the operation of pipe-laying devices against the walls of the trench and its impacts on the bottom are not allowed [6, p. 275].

Backfilling of the trench into which the pipeline is laid is allowed only after control measurements confirming that the pipeline is laid at design elevations (for this purpose, the bottom of the trench is filled with soft soil (fine sand) at a height of 20 cm before laying the pipes), and hydraulic testing of the laid pipeline.

2.7. Fixing at design elevations

Fixation at design elevations is performed by hanging of weighting concrete loads (UBO - 3) on the pipeline. Load hanging is performed by means of crane after insulation laying works. Tilting of loads is not allowed.

According to paragraph 7.12 of the recommendation [2, page 40], it is allowed not to make lining for weighting reinforced concrete loads, provided that there is a protective wrapper. In our project, the protective wrapper is a layer of brizole of increased strength of the BR - II brand.

Лист 1.cdw

Лист 2.cdw