COMPARE COSTS OF MATERIALS

The cost comparison should be made by comparing the cost / or mechanical strength, comparison should be made between the adjusted prices to be multiplied by the price per kg weight divided by the specific allowable stress of each material.

 
When comparing costs of materials should also be taken into
consideration the following points:

1.  Resistance to corrosion;
2.  More or less difficulty in welding;
3.  More or less ease of shaping and working; 
4. Whether or not need stress relief;

  

ON COST OF MATERIALS

Materials                                                         Relative Cost
                                                

Carbon Steel Structural                                       1.00
Cast iron                                                           0.95
Qualified carbon steel                                         1.15
aluminum                                                          2.5
Alloy Steel 1.25 Cr - 0.5 Mo                                  3.1
Aluminum brass                                                  7.6
Stainless steel type 304                                     11.5
Monel Metal                                                      31.8
Stainless steel type 316                                     15.0
titanium                                                           41.0

  

CARBON STEEL PIPES

 LOW COST

 EXCELLENT QUALITY MECHANICAL     

 WELDING AND EASY TO CONFORM

Represents 90% of Pipe Industries

 USED ​​FOR:
Fresh water, steam, condensate, compressed air, oil,
gases and many other slightly corrosive fluids.

 LIMITS OF TEMPERATURE FOR WORK

•  450 º C for severe service
•  480 º C for service  not severe
•  520 º C maximum peak
  
• 370 ° C creep flow begins
• 530 ° C severe oxidation (scaling)
• -45 ° C becomes brittle

THERE ARE SPECIAL CARBON STEEL FOR LOW TEMPERATURES
MORE WITH LESS CARBON AND MANGANESE;

FOR TEMPERATURES BELOW 0 º C and 400 º UP IS RECOMMENDED THE USE OF CARBON STEEL calmed (1% Si).

The CARBON STEEL EXPOSED TO SUFFER THE ATMOSPHERE UNIFORM CORROSION (rust) AND DIRECT CONTACT WITH THE GROUND CONCERNED PENETRATING  PITTING.

A GENERAL METHOD HAS LOW CARBON STEEL CORROSION RESISTANCE (use with coated or play with higher thickness)

 WASTE OF CORROSION OF CARBON STEEL ARE NOT TOXIC BUT MAY AFFECT THE COLOR AND TASTE OF FLUID DRIVEN.

 The CARBON STEEL is attacked violently from MINERAL ACIDS, diluted or ESPECIALLY WHEN HOT AND REASONABLY SUPPORTS THE SERVICE with alkali.

THE CARBON STEEL TUBES ARE SOLD WITHOUT TREATMENT (BLACK TUBE) OR PROTECTED WITH ZINC COATING DEPOSITED HOT (GALVANIZED PIPE).

 LEAGUE STEEL PIPES AND STAINLESS STEEL 

 Pipes alloy steels and stainless steels are much more expensive than carbon steels, in addition to welding, forming and assembly are also more difficult and more expensive.

 GENERAL EMPLOYMENT CASES
high temperatures
low temperatures
high corrosion
Need for non-contamination
security

 Definitions:

 The alloy steel are all other steels containing elements other than those which comprise the carbon steel.

 Alloy steel, piping, stands out two important classes:

•  Improves creep resistance at high temperatures;
  
•  Improved oxidation resistance at low temperatures;

Stainless steels are those containing at least 12% chromium which give them the property not to rust even on prolonged exposure in a normal atmosphere.

 

 Stainless steels can be;

•  AUSTENITIC (non-metallic)
  
  • Intergranular corrosion by the precipitation of Cr carbonetode - sensitization (T> 450)
  •  Corrosion caused by alveolar ion chloride (chlorides, hypochlorite etc.). 
   
•  FERRITIC (magnetic)