How to treat the welds of process pipelines using pickling paste? Urgent!

The instructions are on the packaging of the acid pickling and passivation paste; after use, it’s sufficient to check the quality using the blue dot testing method

Wipe it on, then rinse off with water. . That’s it. .

Wipe it on, rinse off with water: lol

I don’t; I have to outsource it to others every time.

Standard Procedure for Acid Washing and Passivation of Stainless Steel 1 Subject Matter and Scope 1.1 Subject Matter This procedure specifies the requirements, methods, and precautions for removing oil and rust from the surfaces of stainless steel containers (including their components), as well as for carrying out acid washing and passivation. 1.2 Scope of Application These procedures apply to the pickling and passivation treatment of chromium and nickel austenitic stainless steel vessels manufactured by our company. 2 Referenced Documents The following referenced standards and documents shall be the latest versions. When the present procedures conflict with new standards or document contents, the conflicting parts shall be governed by the relevant provisions of the latest standards and documents. \"General Rules for the Manufacturing of Stainless Steel Pressure Vessels\" \"General Inspection Rules\" 3 Acid cleaning and passivation process: Oil removal, dirt cleaning, rinsing with clean water, passivation, rinsing with clean water again, and drying. 4 Pre-treatment before acid cleaning and passivation: 4.1 For stainless steel vessels or components that have been manufactured, acid cleaning and passivation pre-treatment can only be carried out after checking that the specified items meet the requirements outlined in the drawings and process documents. 4.2 Clean the weld seam and the slag and spatter on both sides of it; use gasoline or a cleaning agent to remove oils and other contaminants from the surface of the machined parts of the container. 4.3 When removing foreign objects from both sides of the weld, use a stainless steel wire brush, a stainless steel shovel, or a grinding wheel for removal; after that, rinse thoroughly with clean water (with a chloride ion content of no more than 25 mg/l). 4.4 When the oil contamination is severe, use a 3-5% alkaline solution to remove the oil, and then rinse thoroughly with clean water. 4.5 The oxide scale on heat-treated stainless steel parts can be removed by mechanical sandblasting; the sand must be pure silicon or alumina. 4.6 Establish safety measures for pickling and passivation, and determine the necessary tools and personal protective equipment. 5 Formulas for pickling solutions, passivation solutions, and pastes 5.1 Formula for the pickling solution: 20% nitric acid (specific gravity 1.42), 5% hydrofluoric acid, with the remainder being water. The above are volume percentages. 5.2 Acid cleaning paste formula: 20 milliliters of hydrochloric acid (specific gravity 1.19), 100 milliliters of water, 30 milliliters of nitric acid (specific gravity 1.42), and 150 grams of bentonite. 5.3 Passivation solution formula: 5% nitric acid (specific gravity 1.42), 4 grams of potassium dichromate, with the remainder being water. The above volume fraction of rest is based on a passivation temperature at room temperature. 5.4 Passivation paste formula: 30 ml of nitric acid (67% concentration), 4 grams of potassium dichromate, along with bentonite (100–200 mesh), which are mixed together until a paste is formed. 6 Acid washing and passivation procedures 6.1 Acid washing and passivation can only be performed on containers or components that have undergone pretreatment. 6.2 Acid pickling is mainly used for the overall treatment of relatively small, unfinished components, and can be carried out by spraying. When the solution temperature is between 21–60°C, check every 10 minutes or so until a uniform white etched finish is achieved. 6.3 The pickling paste is mainly suitable for large containers or local treatment. At room temperature, apply the pickling paste evenly and thinly over the equipment (to a thickness of about 2-3 mm). After waiting for one hour, gently brush it away using clean water or a stainless steel brush until a uniform white etched finish is achieved. 6.4 Passivation solutions are mainly suitable for the overall treatment of small containers or components; immersion or spraying methods can be used. When the solution temperature is between 48–60°C, inspections should be carried out every 20 minutes, while when the temperature is between 21–47°C, inspections should be done hourly, until a uniform passivation film forms on the surface. 6.5 The passivation paste is mainly suitable for large containers or local treatment; apply it evenly to the surface of the pickled container at room temperature (about 2-3 mm thick), and check after 1 hour until a uniform passivation film has formed on the surface. 6.6 After pickling and passivating containers or components, their surfaces must be rinsed thoroughly with clean water. Finally, test any area of the rinsed surface using acidic litmus paper to ensure that the pH value is between 6.5 and 7.5, after which the surface should be dried either by wiping or with compressed air. 6.7 After acid washing and passivation, containers and components must not be subjected to impacts or scratches that could damage the passivation layer during handling, lifting, and storage. 7 Precautions 7.1 When preparing the solution, water should be added to an acid-resistant container in the proper proportions, and then acid should be added slowly in the same proportions, to prevent splashing that could cause injury due to too rapid addition of acid. 7.2 Acid washing and passivation: For the first time, testing should be carried out first on a small area of a component or on similar materials. 7.3 During the pickling process, operators must be meticulous and observe carefully to prevent excessive corrosion of the container surface. Effective measures should be taken to prevent carbon steel components from corroding. 7.4 After pickling, the stainless steel surface shall show no obvious signs of corrosion, no patches with uneven coloring, and the welds and heat-treated surfaces shall be free of oxidized colors. 7.5 Operators must wear acid-resistant clothing, gloves, masks, and protective goggles while operating. When carrying out pickling inside a container, it is necessary to wear a gas mask that has passed inspection, and the operation must be conducted under the supervision of a qualified person. 7.6 Austenitic stainless steel components requiring corrosion resistance shall undergo heat treatment as specified in the drawings, followed by pickling and passivation. 7.7 The acid washing and passivation formulas, as well as the operating procedures, concentration ratios, volume ratios, liquid temperature, and operation time mentioned above can be adjusted slightly as appropriate depending on the circumstances. The pickling and passivation solution can be reused, but it is necessary to maintain the appropriate concentration and volume ratio.