Abstract: A spanner wrench for tightening, or loosening, of pipe coupling assemblies, particularly in tight quarters. The wrench comprises a semi-cylindrical base, an arcuate aligner, and a handle that is secured to the base for applying rotational torque to the tool. The base has a plurality of notches defined in its leading edge so that the tool may be slipped into engagement, in an axial fashion, with the lugs on a pipe coupling. The arcuate aligner possesses a radial dimension of sufficient size that the combined height of the aligner and base is equal to the distance that the pipe coupling rises above the run of the pipes to be joined together.