A side lift spreader for lifting an intermodal transport container, the spreader comprising a main beam extending in a longitudinal direction (L); a pair of container locking arrangements , each of said container locking arrangements being located at a respective longitudinal end of the spreader and being configured to be connected to a respective top corner casting of the container ; and a container side support configured to support a longitudinal side of the container at a position vertically lower than the pair of container locking arrangements , the spreader being characterized in that the main beam comprises a vertical carrier plate , the longitudinal axis of which extending in said longitudinal direction (L), the carrier plate having a first vertical height (H 1 ) and being made of steel plate having a first thickness (T 1 ); a C-beam extending in the longitudinal direction (L) and comprising, as seen in cross-section, a first horizontal flange and a second horizontal flange interconnected by a vertical web portion , the C-beam having a second vertical height (H 2 ) lower than the first vertical height (H 1 ) and being made of steel plate having a second thickness (T 2 ) thinner than the first thickness (T 1 ), the first flange of the C-beam being welded to the carrier plate along a first longitudinal weld and the second flange of the C-beam being welded to the carrier plate along a second longitudinal weld such that the C-beam defines, together with the carrier plate , a closed channel beam with a first flange of the carrier plate extending vertically from the closed channel beam; and an elongate, inclined support plate extending along the longitudinal direction (L), the support plate being welded to the carrier plate along a third longitudinal weld , and to an outer face of the first flange of the C-beam along a forth longitudinal weld , the fourth longitudinal weld being located at a distance from the carrier plate . a main beam extending in a longitudinal direction (L); a pair of container locking arrangements , each of said container locking arrangements being located at a respective longitudinal end of the spreader and being configured to be connected to a respective top corner casting of the container ; and a container side support configured to support a longitudinal side of the container at a position vertically lower than the pair of container locking arrangements , the spreader being characterized in that the main beam comprises a vertical carrier plate , the longitudinal axis of which extending in said longitudinal direction (L), the carrier plate having a first vertical height (H 1 ) and being made of steel plate having a first thickness (T 1 ); a C-beam extending in the longitudinal direction (L) and comprising, as seen in cross-section, a first horizontal flange and a second horizontal flange interconnected by a vertical web portion , the C-beam having a second vertical height (H 2 ) lower than the first vertical height (H 1 ) and being made of steel plate having a second thickness (T 2 ) thinner than the first thickness (T 1 ), the first flange of the C-beam being welded to the carrier plate along a first longitudinal weld and the second flange of the C-beam being welded to the carrier plate along a second longitudinal weld such that the C-beam defines, together with the carrier plate , a closed channel beam with a first flange of the carrier plate extending vertically from the closed channel beam; and an elongate, inclined support plate extending along the longitudinal direction (L), the support plate being welded to the carrier plate along a third longitudinal weld , and to an outer face of the first flange of the C-beam along a forth longitudinal weld , the fourth longitudinal weld being located at a distance from the carrier plate . <EOS>