HONG KONG (AFX-ASIA) – Piped gas distributor Panva Gas Holdings Ltd (8132.HK) plans to raise up to HK$503.1 million through a new-for-old placement of 108.9 to 117 million shares at HK$4to 4.3 each, according to market sources. (US$1=HK$7.76). The sources said the company may increase the size of the issue because a pilot marketing exercise…