On 11th, March, 2025 we quoted alloy steel stub bolts and nuts to one France customer. This is the second time that we quoted them. The customer showed their preference to our offer style and expressed that they’d like to cooperate with us one day. This time, after receiving quotation, the customer confirmed some length and quantity details and replied that they would revert back once there’s new progress. Two months later, we received purchase order. They ordered some items in the inquiry.
ZIZI specialize in selling all kinds of pipe fittings, tubes, plates, flanges, bolts and nuts, our products are widely used in many fields, from precision machinery manufacturing to warm home decoration and even high-end aerospace industry. We have become a trusted choice for many industries due to our superior product quality and wide range of applications. Not only do we offer a wide range of products, but we can also provide customized processing services according to the specific needs of our customers, ensuring that your expectations are accurately met every time we work together. With advanced production equipment and strict quality management system, we are committed to providing high-quality piping solutions to customers worldwide. Welcome to contact us.
Purchase Lists
| 1 | SCREW,CAP;SZ 1/2-13 IN*2 IN;ASTM 354 SIZE: 1/2 IN-13 TPI LENGTH: 2 IN MATERIAL: ALLOY STEEL THREAD_TYPE: UNC HEAD_TYPE: HEX | 10 | BOX |
| 2 | STUDBOLT;SZ 5/8 IN;105MM LG;B7;U THD SHORT_NAME:STUDBOLT SIZE:5/8 IN THREAD_TYPE:U LENGTH:105MM | 240 | EA |
| 3 | STUDBOLT;SZ 5/8 IN *11 THD;6 IN LG;ALY SIZE:5/8 IN DIA*11 THD THREAD_TYPE:UNC LENGTH:6 IN THREAD_LENGTH:ALL THREAD MATERIAL_SPECIFICATION:ASTM A193 B7,ASTM A193,ASTM A194 FINISH:TFE COATED | 55 | EA |
| 4 | BOLT;HEX;7/8-9X2-1/4IN;SS;A193 B7;TFLN SHORT_NAME: HEXAGONAL BOLT HEAD_TYPE: HEXAGONAL SIZE: DIAMETER: 7/8 IN THREAD SIZE: 9 TPI LENGTH: 2-1/4 IN | 290 | EA |
Dimension Inspection of Bolts and Nuts
Bolts size:
Nominal diameter (d): calipers or micrometers to measure the thread diameter, the error needs to be within the standard allowable range.
Length (L): measure the distance from the top of the head of the bolt to the end of the screw (all-thread bolts to measure the length of the thread), the tolerance needs to be in line with the requirements;
head size: the head of the opposite side of the width (s), the thickness (k), measured by calipers, to ensure that the nut or wrench with the match.
Nuts size:
Nominal Diameter (D): Measure the small diameter of the thread, and the bolt thread match;
Thickness (m): the height of the nut, affecting the length of the thread engagement, need to meet the standard;
Width of the opposite side of the (s): the size of the wrench with the allowable error in the range.
Thread accuracy inspection:
Use thread pass/stop gauge (plug gauge to measure bolt external threads, ring gauge to measure nut internal threads) to detect: the pass gauge should be able to be screwed in smoothly, and the stop gauge should be screwed in at a length of not more than 1-2 threads (according to the standard);
If necessary, use the thread micrometer to measure the thread center diameter to ensure that it is in the tolerance range (the center diameter has a direct impact on the looseness or tightness of the thread fit).
ASTM A193 Grade B7 Stud Bolts
ASTM A193 is a standard specification covering alloy steel and stainless steel bolting materials for pressure vessels, valves, flanges, and fittings used in high temperature or high pressure service conditions. Among them, B7 is the most commonly used grade.
ASTM A193 Grade B7 Stud Bolts Specification
| Standard Specification Of | ASTM A193 Grade B7 Stud Bolts |
| Type Of Head | Hex, Threading, Square, Round |
| Size Type | Inches 3/8 to 3 |
| Surface Finish | Plain / Zinc plated / Hot dip galvanized |
| Standard Dimensions Of | ASME B18.2.1 |
ASTM A193 Grade B7 Chemical Composition
| CHEMICAL | LIMITS | C | Mn | P | S | Si | Cr |
| ASTM A193 Grade B7 | MIN | 0.37 | 0.65 | 0.15 | 0.75 | ||
| MAX | 0.49 | 1.10 | 0.035 | 0.040 | 0.35 | 1.20 |
ASTM A193 B7 Mechanical Property
| Grade | Size | Tensile ksi, min | Yield, ksi, min | Elong, %, min | RA % min | HBW | HRC |
| B7 | Up to 2-1/2 | 125 | 105 | 16 | 50 | 321 max | 35 max |
| 2-5/8 – 4 | 115 | 95 | 16 | 50 | |||
| 4-1/8 – 7 | 100 | 75 | 18 | 50 |
ASTM A354 Nuts
The STM A354 standard mainly defines the chemical and mechanical property requirements for quenched and tempered alloy steel bolts, studs and other externally threaded fasteners, which are generally 4 inches in diameter and below and are used in services requiring high strength and limited high-temperature applications. The standard itself does not directly specify the brand of nuts, but recommends specific nut brands under the ASTM A563 standard for use with A354 bolts to ensure that the expected load-bearing capacity and reliability can be achieved when the bolt and nut are combined.
ASTM A354 Grades
| Type | Description |
| Grade BC | ASTM A354 Grade BC is similar to BD with little lower strength. |
| Grade BD | ASTMA354 Grade BD should be considered for anchor bolts,threaded rods,other styles of headed bolts,and bolts larger than 1-1/2″ diameter where similar mechanical properties are desired. |
ASTM A354 Nuts Chemical Composition
| Element | Sizes 1/4 to 1-1/2 | Sizes above 1-1/2 |
| Carbon | 0.30 – 0.53% | 0.35 – 0.53% |
| Phosphorus (max) | 0.04% | 0.04% |
| Sulfur (max) | 0.04% | 0.05% |
ASTM A354 Nuts Mechanical Property
| Grade | Size | Tensile, ksi, min | Yield, ksi, min | Elong %, min | RA %, min |
| BC | 1/4 – 2-1/2 | 125 | 109 | 16 | 50 |
| 2-5/8 – 4 | 115 | 99 | 16 | 45 | |
| BD | 1/4 – 2-1/2 | 150 | 130 | 14 | 40 |
| 2-5/8 – 4 | 140 | 115 | 14 | 40 |
Application Scenarios
Industrial manufacturing: mechanical machine tools, automobiles, ships, aerospace and other equipment parts fixed (such as engine block, chassis frame);
Construction: steel bridge, housing frame, pipeline bracket connection
Daily necessities: furniture assembly, home appliances, bicycles, medical equipment, etc.
Special environments: chemical pipelines, nuclear power equipment, marine platforms, etc., the need for corrosion-resistant, high-temperature-resistant special materials Bolts and Nuts
Installation and Maintenance Precautions
Matching: The specifications and strength level of bolts and nuts must be matched exactly to avoid fracture due to mismatch of strength (e.g., high-strength bolts with low-strength nuts may lead to nut slippage).
Pre-tightening force control: When tightening, the pre-tightening force should be controlled according to the design requirements, too loose may lead to loosening of the connection, and too tight may cause the bolt to fracture or deformation of the connected parts (torque wrenches should be used on important occasions).
Anti-loosening measures: In the vibration environment, anti-loosening nuts, spring washers, spot welding and other ways to prevent loosening.
Corrosion protection: In wet or corrosive environments, it is necessary to choose stainless steel materials or surface treatment of bolts and nuts (such as galvanized, chrome-plated, coated with antirust paint).