We have just completed India’s first project for external coating of LPG Mounded Bullets with 100% Solids Polyurethane Coating (dated 2003) for Indian Oil Corporation Ltd., a Fortune 500 company at Chengelpet (Tamil Nadu). Prior to this, Coal Tar Epoxy was being used with quite poor results and several major defects.
The surface was blast cleaned to SSPC SP-10 with an anchor profile of 75-100 microns using granulated copper slag abrasive, primed using Purethane® AR Primer and coated with Purethane® coating to a thickness of 1,000 microns. Regular field tests were conducted for film thickness (DFT – ASTM E 376) using Positest or Elektrophysik gauges; For Adhesion (ASTM D-4541) using Positest ATCM, and for Hardness (ASTM D-2240) using Durometer with 100% of the results conforming to specification. Amchem’s skilled application crew and state of the art high capacity equipment did an excellent job as the coating was tested for holidays in accordance with NACE 0188-90 using Tinker – Rasor high voltage holiday detector and a pinhole free coating was provided and the current consumption by the Cathodic Protection (CP) system was negligible.
The client was very pleased with the performance of Purethane and our swift and professional application service (and since 2003, they have specified 100% Solids Polyurethane Coatings for all of their future projects).
Since this first project, Purethane Coatings have emerged as the coating of choice across the industry. Presently direct to metal Polyurethane are being recommended for these applications due to their ability to withstand the very high Cathodic Protection currents being applied due to wet mounds and current leakage. For Mounded Bullets the coating application is being done by the fabricators of the bullets. Hundreds of Mounded Bullets have been completed by these companies for Indian Oil Corporation, Hindustan Petroleum Corporation, Bharat Petroleum, Bharat Oman Refinery, HPCL – Mittal Energy etc in Refineries and Bottling plants across the country.
Presently, Purethane PLX (which meets the European standard EN 10290) is recommended for external coating of LPG Mounded Bullets. Some key features of it are:
- Direct to Metal, faster production
- Harder coating, higher adhesion
- Lower permeability
- Very low cathodic disbondment
- Microbial resistance
- Higher resistance to electro-endosmosis and excessive currents due to inefficient Cathodic Protection systems