1. Read and memorize following words and expressions:

• Copper pipes - мідні труби

• To fix - з’єднувати

• Cheap - дешевий

• Domestic - домашній

• To guard against - захищати від

• To isolate - ізолювати

• To allow - допускати

• Soil - земля

2. Read, translate and study the text:

Pipe Materials.

Copper pipes are permitted for use inside premises subject to the gauge complying with water company's regulations. Such pipes are simple to fix and have a neat appearance.

Galvanized wrought-iron pipes may or may not be permitted. Some authorities will only allow such pipes on the outlet side of a metered supply. Where the water is of a hard nature they may be safely used. Galvanized wrought-iron pipes, though cheap, are little used for domestic supplies.

There are three grades of iron pipes, known as "gas", "water" and "steam" strengths, and for water supplies the steam quality should be specified. Whatever type of service pipe is laid, it should be at a

reasonable depth below the surface of he ground, usually not less than 2 ft. 6 in., to guard against the effects of frost.

Mains are tapped under pressure by a special machine consisting of a watertight box which is attached the main by means of a chain. The hole is drilled and tapped.

This method allows the work of a connection to be made without shutting off the water in the main. They may allow the pipe through foul soil, provided the pipe is sufficiently protected from contact with soil.

3. Arrange the words in pair of synonyms:

• Fierce

• Reserved

• Insult

• Make

• Steady

• Firm

• Sincere

• Load

• Frank

• Mold

• Uncommunicative

• Violent

• Burden

• Indignity

• Solid

• Balanced

4. Make up 5 sentences with the words:

Pipe, to use, to be permitted, gas, water, steam

5. Work in pairs:

Ask your group-mat e about the :

1. copper pipes

2. three grades of iron pipes

3. mains

6. Answer the questions:

1. Are copper pipes are permitted for use inside subject?

2. May galvanized wrought-iron pipes be permitted?

3. What are three types of iron pipes?

4. What should the depth of pipes laid be?

5. The hole is drilled and tapped, is not it?

7. Agree or disagree with the statements:

• Mains are tapped under water.

• There are three grades of iron pipes: gas, water and steam,

• The hole is drilled and is not tapped,

• This method does not work without shutting off the water.

Unit 19

Stress Corrosion Cracking.

1. Read the text and try to understand the main idea.

Stress corrosion cracking (SCC) is the unexpected sudden failure of normally ductile metals subjected to a tensile stress in a corrosive environment, especially at elevated temperature in the case of metals. SCC is highly chemically specific in that certain alloys are likely to undergo SCC only when exposed to a small number of chemical environments. The chemical environment that causes SCC for a given alloy is often one which is only mildly corrosive to the metal otherwise. Hence, metal parts with severe SCC can appear bright and shiny, while being filled with microscopic cracks. This factor makes it common for SCC to go undetected prior to failure. SCC often progresses rapidly, and is more common among alloys than pure metals. The specific environment is of crucial importance, and only very small concentrations of certain highly active chemicals are needed to produce catastrophic cracking, often leading to devastating and unexpected failure. The stresses can be the result of the crevice loads due to stress concentration, or can be caused by the type of assembly or residual stresses from fabrication (e.g. cold working); the residual stresses can be relieved by annealing.