A fitting assembly for liquids adapted to be installed in a pipeline includes an inlet and first shut-off governing said inlet, an outlet and second shut-off governing said outlet, and components which require occasional or regular servicing arranged in a flow path between said first and second shut-offs. The said fitting assembly comprises a first fitting part adapted to be fixedly installed in said pipeline by means of said first and second shut-offs, said first fitting part having first and second connections between said first and second shut-offs, said fitting assembly comprises a second fitting part, said second fitting part containing the components which require occasional or regular servicing, and a means for removably attaching said second fitting part to said connecting means of said first fitting part.