A globe type Y-pattern diaphragm valve for high pressure, high temperature service affording increased diaphragm cycle life, enhanced flow coefficient and features of decreased construction cost. Comprising the diaphragm in one embodiment is a resiliently supported multi-layer cartridge formed of superimposed layers of different metals having different moduli of elasticity with the upper layers being radially slotted to redistribute encountered stress loads. In an alternate embodiment the multi-layer diaphragm cartridge is comprised of superimposed layers of like composition but of varying relative thicknesses and supported to afford a controlled flexure. An auxiliary porting in the discharge passage adjacent the valve head in combination with a downstream tapered and faired beltway effects a more nearly streamlined flow path to increase the flow coefficient rating of the valve. By means of a multi-purpose packing gland identically threaded both inside and out, the gland is able to also function as a stem bushing enabling a comparatively inexpensive bar stock bonnet construction to be employed.