Material Selection for organic solvent

I am inspection engineer working for Polyvinyl chloride resin manufacturing facility in Pakistan. One of the chemicals that we use is CH1, chemical formula is C6H3(C4H9)(OH)2 also known as 4-Tert-Butylcathecol. This chemical is dissolved in methanol [affil link] (the ratio by weight is 30% CH1 and 70% Methanol). Now the problem is that the piping for this mixture is Carbon Steel (A-106 Gr.B). We've witnessed corrosion on this piping and had three pinhole leakages in an interval of a year. The information that I want from you is that what would be a suitable and economical material for this service. CH1 is an organic solid acidic and methanol is an organic solvent. The PH of this mixture is 2~4. Kindly recommend an appropriate piping material. I'll further narrow down my query and ask whether SS304L is the right material. Looking forward to an urgent response.

304 will be a much better choice than mild steel. A better choice would be 316L which is considerably more acid resistant than 304. Be sure that the welds are also done in L or LL grade 316.