Industrial Pipeline Degreasing Process

1 range

This standard applies to metal pressure piping engineering design documents, must be degreased oil pipe, pipe fittings, valves, gaskets, fasteners and other piping components and instrumentation degreasing construction.

2 normative reference documents

The provisions in the following documents become the provisions of these rules by reference. All dated reference documents and their subsequent revisions (excluding errata), or whether or not this procedure should be applied, shall be determined by the preparation of the specialized department after the study. The latest version of the undated reference document applies to this specification.

GB20801-2006 "Pressure piping tables - Industrial piping

GB 97-50235 Specification for the Construction and Acceptance of Industrial Metal Piping Projects

SH / T3517-2001 "Technical Specification for the Construction of Petroleum and Chemical Pipeline Engineering Steel Pipe Engineering

SH3501-2002 Standard for Construction and Acceptance of Petrochemical Toxic and Flammable Media Pipelines

HG20202-2002 "Construction and acceptance of degreasing works"

3 Construction preparation

3.1 Material requirements

3.1.1 When a design is provided, the design shall be based on the design of the fatting agent to be used. When not specified in the design, it is preferable to use industrial trichloroethylene as the degreasing agent, considering safety and degreasing effectiveness. A range of commonly used degreasers may also be listed in Table 1, depending on customer requirements or for other reasons.

3.1.2 Alkaline degreasing fluids are listed in Table 2, Table 3 for preparation and use; emulsions (see Table 4) and steam are also available.

3.1.3 Chemicals used as fat absorbers or for detergents should have a qualified manual.

3.2 Construction equipment and tools

3.2.1 Equipment: acid-resistant pumps, temporary pipes, etc.

3.2.2 Tools: plastic buckets, basins, brushes and necessary labor protection materials.

3.2.3 Tools: solvent tanks (which can be made from stainless steel pipes), fittings for connecting temporary lines, valves and cleaning lines.

3.2.4 Portable Fluorescence Detector, White Paper.

3.3 Operating conditions

3.1.1 Pipes, fittings, valves, gaskets, fasteners, etc., such as pipe assemblies and instruments, that require degreasing have passed inspection and acceptance.

Table 1 Common degreasers

Name of the fatty agent

Scope of application

note

Industrial dichloroethane

metal part

Hydrolysable to trace amounts of hydrochloric acid

Industrial trichloroethylene

metal part

Pure carbon trichloride stabilizer, non-corrosive to common metals

Industrial Alcohol

Less demanding equipment and parts

The fat is weak.

65% above concentrated nitric acid

Acid fittings for concentrated nitric acid units

Strong oxidizers that dissolve or dissolve certain metals.

Alkaline degreasing solution (see Tables 3.1.2-2 and 3.1.2-3).

Simple shape, easy to clean pipes

It is not suitable for precision parts and metal parts with surface conversion layers.

Table 2: Proportion and process conditions for hot alkali degreasing

serial number

Composition (g/l)

Removal temperature (°C)

Clearance time (minutes)

1

Sodium hydroxide 50 sodium phosphate 30 sodium carbonate 30 sodium carbonate 5

100

30~40

2

Sodium hydroxide 30 Sodium phosphate 15 Sodium carbonate 5 Sodium carbonate 15

85~95

20~30

Table 3: Formulation and conditions of alkaline degreasing solution

serial number

Formulation (weight %)

Scope of application

1

Sodium hydroxide O.5-5 sodium phosphate 10-3 sodium silicate 1-4

General Steel Parts

2

Sodium hydroxide 2-5 sodium phosphate 1-8 sodium silicate 3

General Steel Parts

3

Sodium hydroxide O.5-3 sodium phosphate 7-2.5 sodium silicate 1-2

Common copper and copper alloy parts

4

Sodium phosphate 5-8 2-3 5 Sodium dihydrogen phosphate sodium silicate 0.5-6-1

Weakly alkaline, with the ability to remove oil, low corrosion to metals

Table 4: Emulsifier formulations for degreasing agents

serial number

names

Weight ratio (%)

1

gasoline

67

2

turpentine

22.5

3

lauric acid

5.4

4

triethanolamine

3.6

5

Dingy Fiber Solvent

1.5

4 Construction techniques.

4.1 Construction procedures are shown in Figure 1.

Figure 1 construction procedures

METHOD: 4.2 Common methods of oil removal are: immersion; immersion. Infiltration; scrubbing; and circulation system.

4.2.1 Immersion method on the inner surface of pipelines

Fill the tube with solvent, either by filling the end of the tube with a wooden block or other blocking method, or by soaking the tube directly in the plate of the degreasing tank for 1 to 1.5 hours, rotating it every 15 min for several weeks so that the tubes can be evenly distributed over the entire surface after multiple cleanings and submersions. The amount of solvent required per meter of pipe is usually 5.

Table 5 Dosage of fat absorbent per metre

Pipe diameter (mm)

15

20

25

32

40

50

65

Solvent volume (L)

0.15

0.20

0.30

0.40

0.50

0.60

0.70

Solvent dipping arc (degree)

251

205

200

179

161

143

116

Pipe diameter (mm)

80

100

125

150

200

250

300

Solvent volume (L)

4.80

4

4.25

4.5

2

2.5

3

Solvent dipping arc (degrees)

110

102

93

87

79

73

68

4.2.2 Scrubbing and skimming of large-diameter pipes and their external surfaces

Plastic tubs or buckets containing solvent cleaner, brushes or grease-free cloths, such as scrubbing silk for scrubbing pipes, long-lasting pipe cleaning ties for two-way scrubbing of pipes.

4.2.3 System circulation

The system has been installed or skimmed to form two types of system contamination that can be used by means of system cycling.

4.2.3.1 The cycling time is based on the size of the system and the diameter of the pipe, the degree of contamination is determined, generally not less than 60 minutes, for larger piping systems, it should be grounded to the temporary piping, temporary piping connections are shown in Figure 2. .

Figure 2 diagram of temporary piping connections for the system cycling method

4.2.3.2 For small-diameter piping systems (e.g., lubricating oil systems), on-site plant wind power may also be used to blow plant wind onto the piping for wind and degreasing media, with temporary piping connections.