Abstract: A plurality of movable temporary hangers 7 are placed on a stay cable 4B hung in tension above a target stay cable 4C, and then the target stay cable 4C is held on a lower portion of the temporary hangers 7. Then, the target stay cable 4C held with the temporary hanger 7 is detached from a bridge deck 3 and a main tower 2. Then, the target stay cable 4C and the temporary hangers 7 holding the target stay cable 4C are moved toward the bridge deck 3 and removed.

Abstract: A plurality of movable temporary hangers 7 are placed on a stay cable 4B hung in tension above a target stay cable 4C, and then the target stay cable 4C is held on a lower portion of the temporary hangers 7. Then, the target stay cable 4C held with the temporary hanger 7 is detached from a bridge deck 3 and a main tower 2. Then, the target stay cable 4C and the temporary hangers 7 holding the target stay cable 4C are moved toward the bridge deck 3 and removed.

Abstract: Provided is a process for the production of high-purity trimellitic acid including subjecting a dimethylbenzaldehyde and/or an oxidized derivative of the dimethylbenzaldehyde to liquid-phase oxidation with molecular oxygen in an aqueous solvent containing a catalyst to produce trimellitic acid, in which: 3,4-dimethylbenzaldehyde and/or 3,4-dimethylbenzoic acid are/is used as a raw material; a catalyst containing 0.05 to 1 part by mass of one or more kinds of metals selected from the group consisting of cobalt, manganese, and nickel, 0.0001 to 0.0015 part by mass of metallic iron and/or iron obtained from a water-soluble iron salt, and 1 to 5 parts by mass of bromine with respect to 100 parts by mass of the aqueous solvent is used as the catalyst; and the liquid-phase oxidation is conducted at a temperature of 200 to 250° C.

Abstract: A method of producing pyromellitic dianhydride. The method includes a step of heating a crude pyromellitic acid in the absence of acetic anhydride to convert a part of pyromellitic acid to pyromellitic anhydride, and a subsequent step of heating the resultant mixture in the presence of acetic anhydride to complete the anhydrization of pyromellitic acid. The pyromellitic dianhydride by the method contains little pyromellitic monoanhydride and other monoanhydrides derived from impurities and is less discolored. The pyromellitic dianhydride has particle properties not causing plugging, etc. during its transportation, storage and use.

Abstract: A method of producing pyromellitic dianhydride. The method includes a step of heating a crude pyromellitic acid in the absence of acetic anhydride to convert a part of pyromellitic acid to pyromellitic anhydride, and a subsequent step of heating the resultant mixture in the presence of acetic anhydride to complete the anhydrization of pyromellitic acid. The pyromellitic dianhydride by the method contains little pyromellitic monoanhydride and other monoanhydrides derived from impurities and is less discolored. The pyromellitic dianhydride has particle properties not causing plugging, etc. during its transportation, storage and use.

Abstract: A process for producing a polycarboxylic acid which comprises performing liquid phase oxidation of polyalkyl-substituted aromatic aldehyde and/or oxide derivative of polyalkyl-substituted aromatic aldehyde as raw material for oxidation with molecular oxygen at two stages in water solvent in the presence of a catalyst comprising bromine or both bromine and a heavy metal(s) at a temperature of 180 to 280 ° C., thereby producing trimellitic acid or pyromellitic acid, wherein said liquid phase oxidation is performed in a continuous operation at the first stage and in a continuous operation or in a batch operation at the second stage and a total amount of bromine in said catalyst is divided to add separately at each the first stage and the second stage.

Abstract: A process for producing a polycarboxylic acid which comprises performing liquid phase oxidation of polyalkyl-substituted aromatic aldehyde and/or oxide derivative of polyalkyl-substituted aromatic aldehyde as raw material for oxidation with molecular oxygen at two stages in water solvent in the presence of a catalyst comprising bromine or both bromine and a heavy metal(s) at a temperature of 180 to 280 ° C., thereby producing trimellitic acid or pyromellitic acid, wherein said liquid phase oxidation is performed in a continuous operation at the first stage and in a continuous operation or in a batch operation at the second stage and a total amount of bromine in said catalyst is divided to add separately at each the first stage and the second stage.

Abstract: A process for the production of a trimellitic acid by oxidizing dialkyl aromatic aldehyde and/or its oxide derivative in a liquid phase, the oxidation being carried out in a lower aliphatic carboxylic acid solvent having a water content of 5 to 70% by weight in the presence of a catalyst containing a heavy metal and bromine or being carried out in a solvent containing a lower aliphatic carboxylic acid in the presence of a bromine-manganese catalyst system containing zirconium and/or cerium, and a process for the production of high-quality trimellitic acid anhydride from the trimellitic acid.