**2.3 Plate material**

It is very important to choose the plate material according to the flow rate used and the maximum desired working strength. Generally, the plate materials given in **Table 1** are used and the most commonly used material type is 1.440 / AISI 316 [2, 3].


**Table 1.** *Material types of heat exchangers.*

PHEXs are produced from different materials in today. These alternative materials are aluminum, carbon steel, stainless steel, nickel alloys, zirconium and titanium. For many chemical processes, Zirconium is a cost-effective material of construction in shielding process equipment systems from destructive corrosive leaks. With incredibly high resistance to corrosion, Zirconium HEXs can withstand some of the harshest situations. This translates to decreased maintenance expense, with downtime kept to a minimum. Copper has many preferred specifications for thermally efficient and durable HEXs. Above all else, copper is an perfect conductor of heat. This means that copper's high thermal conductivity allows heat to pass through it speedly. Other required specifications of copper in HEXs include its corrosion resistance, biofouling resistance, maximum allowable stress and internal pressure, creep rupture strength, fatigue strength, hardness, thermal expansion, specific heat, antimicrobial specifications, yield strength, high melting point, ease of fabrication, and ease of joining.

In chemical processes, the use of titanium HEXs has been found to be a costeffective method of resisting leaks from corrosion on a process line. Titanium HEXs has superior corrosion resistance, high heat transfer efficiency, non-breaking property and provide an extended service life compared to other materials.
