Long-term performance of PPS Dual Laminates Used for Hot sodium Hydroxide in a chlorine electrolysis Plant

摘要

On the basis of the analysis outlined above, the five questions asked earlier can be answered as follows: PPS shows a 100 percent chemical resistance against 50 percent NaOH at 110 to 130 deg C after three years of continuous service. There is no indication of any lifetime restricting influences so far. NaOH does not migrate through PPS. All results gained in this study agree with those gained in phase one and the lab-scale findings. Vinyl ester resin shows an improved performance under the given service conditions. Rod-welded flanges can be used alternatively to flaring techniques, as long as welding is done properly. Poor welding leads to a risk for immersion of NaOH into the interface of PPS/FRP, followed by corrosion of the glass bonding and possible de-lamination of the FRP. According to this long-term field test, linear unfilled (high molecular weight) PPS appears to be suitable for piping systems conveying 50 percent NaOH at 130 deg C.