The role of a block valve is to fully open or fully close a pipeline. Block valves are not subjected to the rigors of throttling in mid-travel positions, and they are operated only occasionally. The less stringent requirements for block valves are generally visible in terms of design sophistication, materials of construction, and construction details. Block valves do, however, include a sealing method that provides tight shutoff. Section 8.2.2 of Saudi Aramco Engineering Standard J-700 requires the use of full-bore gate, ball, globe, or butterfly valves as block valves. The requirement for a full-bore valve design ensures maximum flow capacity. In contrast, the role of a control valve is to modulate flow; accordingly, very few control valves are of a full-bore design. Block valves, are typically installed in bypass arrangements (refer to Figure 2). A typical bypass arrangement includes valves that direct flow around a control valve or other device to allow removal or repair of the control valve or other device without a shut down of the system. Block valves are often manually operated with handlevers or handwheels.