For the use of 2304 duplex in place of Ferritic 444 for the production of high pressure solar water heaters
Solar PriMeg has been manufacturing Solar Water Heaters since 1993. It is one of the oldest solar manufacturers in KwaZulu-Natal and in the country. It is based in Durban, which remains its target market, but has units throughout South Africa. The company has exported units to four other countries.
Solar PriMeg was the first company in South Africa to introduce the non-pressure flat panel collector system as a local competitor to the imported products. This won the company the Innovation Award in the 2012 Stainless Steel Awards.
Solar PriMeg manufactures flat plate collectors only. This is a 100% local content product and it believes that this technology should be used as an alternative to the imported product. Solar PriMeg uses the highest quality stainless steel to manufacture the nonpressure, semi pressure and the high pressure solar tanks. All the conversion and welding is also done within its factory.
Solar PriMeg’s systems have passed SABS standards. The company works closely with Test Africa and the SABS testing labs and has continuously improved its solar system on both a quality and performance basis.
Move from Ferritic to Duplex Stainless Steel
Solar PriMeg has been experimenting with lean duplex material since 2010. An opportunity in 2013 saw the company use grade 2304 duplex in the production of its high pressure solar water heaters and found many benefits as compared with ferritic 444.
Solar PriMeg is the first manufacturer in the solar / water heating industry in Africa that is using the duplex 2304.
Due to the higher yield strength of 2304 duplex, Solar PriMeg was able to down gauge the stainless steel thickness from 1.5mm to 1.0mm. Duplex is almost double the yield strength of the ferrittic material which means using the duplex material was the same as using 2.0mm 444 material. This is an advantage as the pressure tank is stronger and will therefore last longer.
By down gauging, Solar PriMeg has benefitted from a cost reduction point of view over the past year. Duplex is more expensive than ferrittic material based on a R/kg basic, but due to the reduction of the mass, the company was able to reduce about 30% of the cost on the components they converted.
The pitting resistance equivalent (PRE) value of the duplex 2304 is better than the PRE for 444. This translates to a more resistant product that offers better quality. This further translates to a longer life span on the solar system, saving the end user.
Solar PriMeg was also able to achieve more finished product or number of sheets from a coil of material than previously. Due to the down gauging, assuming the coil weight remains constant, we are able to get 30% more sheets than using 444 at standard gauge. This translates to increased productivity and further reduction in operational costs.
Due to the higher yield strength of the duplex material, even with the down gauging the total material strength of the vessel was increased as compared to ferrittic 444. This was a win, win, win, win situation for Solar PriMeg. It was very rare that a project such as this offered cost effectiveness with improved quality across multiple aspects of design together with increased productivity.
Solar Primeg – 031 502 5838