Surface Preparation for Structural Steel

Dear Readers,

Effective life of coating of anti-corrosive paint applied to a steel surface is to a very large extent dependent on how thoroughly the surface has been prepared prior to painting.

 

Removing contamination and increasing surface roughness will allow maximum bond strength and adhesion to develop between coating and substrate. If the coating is applied to a well prepared substrate, they will have strong adhesion to that substrate and may be able to withstand these condition.

 

Coating performance is directly related to the quality of surface preparation.

 

Method of Surface Preparation 

1.       High Pressure Fresh Water Washing

2.       Solvent Cleaning or Degreasing

3.       Manual methods of Surface Preparation

4.       Power tool Methods of Surface Preparation

5.       Dry Abrasive Blasting

6.       Rotary or Wheelabrator blasting

7.       Slurry Blasting

8.       Hydro blasting

Blasting Standards

1.       ISO Standard (8501-1)

2.       Swedish Standards ( SIS 05 59 00)

3.       Steel Structure Painting Council Standards (SSPC-SP)

4.       British Standards Institution (BS4232)

5.       NACE Standards (National Association of Corrosion Engineers)

6.       JSRA Standards (Shipbuilding Research Association of Japan)

7.       Major Local Shipyard Standards

Wire Gauge Table

Dear Readers,
 
Gauge systems and are used to represent the thickness of the wire or diameter of the wire. In Great Britain wire gage has been legalized. Following gauges are available in industrial usage. 

   1. British Sheet & Hoop Iron Standard Gauge (Birmingham Gauge)

   2. U.S.Standard Gauge for Sheet & Plate Iron & Steel

   3. Birmingham Wire Gauge (or Stabs'iron  wire or Warrington Gauge)

   4. British Imperial Standard Wire Gauge

   5. American Steel & Wire Co.(or Washborn & Moen or Rocbling or Steel Wire Gauge)

   6. Washbrn & Moen Steel Music Wire Gauge

   7. New American Steel & Wire Co. music Wire Gauge

   8. American or Brown & Sharpe Wire Gauge

Dimensions of above said wire gauges are listed below. Specific usage are mentioned bottom of the table (Represented as Column-2, Column-3, etc.,). All dimensions are in mm. Click on Picture to enlarge

 

Column-2 : Used in great Britain for sheets and strips but in the United States only for strips (for black sheet see columns 3 and 4)

Column-3 : This gauge is used in the United States for black sheet

Column-4 : Used in Great Britain and the United States for wire (in the United States also used for black sheet and strips)

Column-5 : Used in Great Britain for iron and steel wire ; in the United States it is also used for copper wire.

Column-6 : The United States Bureau of Standards combines these gauges under the name " Steel Wire Gauge. "This is the most widely used gauge for wire in the United States.

Column-7 & 8 : For music wire

Column-9 : Used in the United States for nonferrous wire and sheets. The fractions have been approximated. 

Overall as the gauge number decreases, the thickness of the wire increases. Note that 000000 are pronounced " Six aught" . Similarly is an abbreviation for 0000 is pronounced " four aught" and so on.

 

Safe Working Load (SWL)

Dear Readers,

SWL is very important and essential for rigging & hoisting works during construction activities and sometimes stated as the Normal Working Load (NWL).

 

It is the mass or the force a piece of lifting equipment, lifting device or accessory can safely utilize to lift, suspend, or lower a mass without fear of breaking. Usually marked on the equipment by the manufacturer and is often 1/5 of the Minimum Breaking Strength (MBS) although other fractions may be used such as 1/4, 1/6 and 1/10. 

The SWL is determined by dividing the minimum breaking strength (MBS) of a component by a safety factor assigned to that type and use of equipment. The safety factor generally ranges from 4 to 6 unless a failure of the equipment could pose a risk to life; in that instance the safety factor would be a 10.

For example, if a line has an MBS of 1,000 pounds and a safety factor of 5, then the SWL would be 200 pounds. 1000/5 = 200.  

Thumb Rule for Determination of SWL of Wire rope slings:

SWL = 8*D²; in Tons; Where D diameter of rope in inches.

Example:

1 Inch diameter rope 1*1*8 = 8 Tons

½ inch diameter rope 0.5*0.5*8 = 2 Tons

Other way to calculate the SWL of any wire rope by

1. Obtained the Breaking strength of the wire rope as per the class.
2. Consider the Safety factor (Generally taken 5 for wire rope, except taken 10 while use for lifting person)
3. Divided the breaking Strength by Factor of safety.

 For More Details about Safety Helmet Click Here