Combined wall systems are used when regular sheet piles are not strong enough to carry the required loads. The two main components of a combined wall system are the king pile and a pair of intermediary sheet piles. The connector is the third component and is welded to or interlocked with the king pile and connects the king pile to the sheet pile. The intermediary sheet piles transfer the soil and water pressures to the king piles, which carry most of the load. The sheet piles are usually shorter, varying from 60% to 100% of the length of the king pile. The king piles are often designed to carry substantial vertical loads in addition to the normal bending loads.