Extra Long Socket Head Cap Screws Stainless Steel

We make extra long socket head cap screws in passivated A2 stainless with a cylindrical head, hexagon socket and half thread, quoting them from M1 to M14. Socket depth, both lengths, shank diameter and grade come from your drawing, and the first article is driven at your joint torque.

Watch the factory video·Email sst@szsst88.com

ISO 9001:2015 · Manufacturing since 1998 · 8,678+ customers · 89 countries and regions

Made to order – there is no stock catalogue. Each part is produced to your drawing, and production starts after drawing review and first-article approval.

What These Screws Are

These extra long socket head cap screws are stainless fasteners with a cylindrical head, a hexagon socket and a half thread, made in lengths that carry them through a deep joint. They are quoted from M1 to M14 with Number 001, and the lengths run from a few centimetres up to the very long sizes used in frames and dies.

Socket cap head. A cylinder with a flat bearing face and an internal hexagon, seated in a counterbore.

Half thread. The plain shank runs through the joint and the thread engages only at the far end.

Long shank. A body long enough to pass a frame, a spacer or a stack and reach the tapped part behind.

Passivated stainless. A2 grade, uncoated, so the socket, the shank and the thread are as made.

Extra long socket head cap screws cover the length that a standard screw cannot: frames, spacers, tooling stacks and outdoor fixtures where the plain shank has to pass several parts before the thread engages at the far end.

What Very Long Changes

At the long end of the range a screw stops being a fastener and starts behaving like a shaft. The shank twists under the key, it springs when the joint is tightened, and it bends if it is handled carelessly. None of that is a defect; it is the behaviour of a slender steel bar, and the joint has to be designed around it rather than against it.

The drive is what makes the length practical. An opposite (cross) recess would cam out as the load rose, and cam-out on a long shank grinds the recess before the thread has done its work; a hexagon socket takes the load on six flats and stays seated. On these parts the socket is the reason the screw can be driven at all.

The half thread keeps the joint working. The plain shank passes the clearance holes, so the parts slide together and stay in line, and the thread engages only at the far end. On a very long screw the plain section is most of the part, and its diameter is what decides whether the screw slides through the stack or binds in it.

Stainless adds one consideration that steel does not. A2 against A2 galls when driven dry under pressure, and the longer the engagement and the higher the torque, the more chance there is. A lubricant at assembly, or a dissimilar grade in the mating part, is the usual control, and on a long screw it matters more than on a short one because there is more thread to seize.

The counterbore is the last piece. A cap head sits in its counterbore with the flat underside on a machined face, and on a long screw that face is what carries the clamp; a pocket that is too shallow holds the head off, and the shank then sits at an angle in its clearance holes.

Sizes, Lengths and Socket

The recorded range is M1 to M14, with lengths made to the drawing; the long end of the range runs to the very long sizes used in frames and tooling. Custom lengths up to 2,000 mm are subject to DFM review after drawing submission. For these screws the quotation carries head diameter and height, socket size and depth, overall length, threaded length and the grade.

Threaded length and plain length are quoted separately. On an extra long screw the division is the joint, and a thread that starts too early grips the stack while one that starts too late does not reach far enough into the far part.

Packing is a real part of the specification at these lengths. A long screw loaded at both ends in a box takes a set, and the parts are supported through the route and packed so the length is not loaded.

Socket Drive, Stainless, Long

Three features define the part: the socket drive, the stainless body and the length. The first lets the torque arrive, the second removes the corrosion question from a long exposed surface, and the third gives the reach.

The stainless body is what makes these practical outdoors. A plated screw rubbed through a dozen clearance holes loses its coating where it matters, and the rust starts along the shank; stainless has nothing to lose.

The cost is galling. A long stainless screw driven dry into a stainless thread can seize with no warning, and a seized screw of this length cannot be cut out easily; the lubricant at assembly is not optional.

Passivated Stainless Along the Length

The recorded finish is passivation with no coating on A2 stainless. On a very long screw that is the right finish because there is nothing to be added: a coating would have to survive being rubbed along the whole shank, and on these lengths it would not. Passivation leaves the surface as made and lets the alloy do the work.

Material and Finish Options for Extra Long Socket Head Cap Screws

Where the joint is marine, A4 is the grade and the socket is the surface to protect: a rusted socket on a very long screw is a screw with no removal route, because the key cannot be made to fit again.

Where cost drives the choice, a coated steel screw works indoors, and the shank is where the coating wears. On a long part that is a cosmetic issue in a dry frame and a corrosion issue in anything damp.

Where These Screws Are Used

Three assemblies where extra long socket head cap screws are the fixing:

Why Shi Shi Tong for These Screws

Four reasons that matter on a very long stainless screw, each tied to what the drawing has to prove:

How These Screws Are Manufactured

Shi Shi Tong makes extra long socket head cap screws on two-die headers that form the cylinder and cut the hexagon, then support the long blank while the half thread is rolled and the parts are passivated. The first part of every run is measured on head height, socket depth, overall length, thread length and shank diameter before the batch continues.

A long blank is the hardest thing on a heading line. It has to be held over most of its length while the head is formed at one end, and any misalignment in the grip shows as a head that runs off the axis; the screw then measures correctly and will not enter a close counterbore.

Inspection: Socket, Shank, Thread

What decides whether these screws pass is the socket, the head, the shank and the thread. The inspection agreement covers those, and the criteria come from the drawing.

Head and socket on the projector	Thread gauged per batch
Hardness checked on the wire	Salt-spray testing of the grade

The socket is checked for across flats and depth, the head for diameter, height and face flatness, and the shank for diameter along its length. The thread is gauged, and the grade is confirmed on the mill certificate rather than by appearance.

The first article is driven into the customer joint with the production key at the joint torque. A screw that measures correctly and stalls at the key is still a part that fails, and only the drive test shows it.

Certificates and Material Documentation

Every shipment of these screws is traceable to the wire it was made from and to the passivation batch. The grade and heat number are recorded on the material certificate supplied with the parts, and the inspection records follow the criteria agreed on the drawing.

ISO 9001:2015	RoHS test report
Registered trademark	Patent: security screw and driver

With each batch we supply the material certificate, the inspection record for the criteria on the drawing and, where it is listed, the third-party report for the grade. The documents carry the drawing revision and the batch number, so a repeat order keeps the same socket and lengths.

Customers and Projects

More than 8,678 customers in 89 countries and regions have ordered from Shi Shi Tong; 87% of orders come from repeat customers and 56% through referrals. Most projects follow the same route: drawing review, first-article approval, then batches checked against that sample. On these screws the first article is driven into the customer joint at the joint torque, because the drive and the plain length are both proved there. Buyers visit during the process to review samples.

Buyers and quality engineers visit for sample review, process discussion and supplier audits; the visit is arranged around production so the two-die headers and the passivation line can be seen on the day the parts run.

Customer group visit – sample review	Customer group visit – process discussion	Customer group visit – factory tour
Customer visit – project kick-off	Danish customer – drawing review	Industry exhibition – meeting customers

Related Products and Guides

Technical Guides

Long Thin Screws: Drawing and Manufacturing Requirements What to put on the drawing for long, thin parts: datum, shank, thread position and handling. Read the guide

How Long Does It Take to Customize Extra-Long Screws? Where the time goes in a custom long-screw order, from drawing review to first article. Read the guide

Products

M6 Pan Head Hex Socket Machine Screws Socket-driven pan head screws up to 630 mm with a partial thread. M6 Pan Head Hex Socket Machine Screws	Partial Thread Machine Screws Partial-thread machine screws with a defined plain shank. Partial Thread Machine Screws	Countersunk Socket-Slotted Screws with Locking Patch Sunk heads with a combined socket-slot drive and a nylon locking patch. Countersunk Socket-Slotted Screws with Locking Patch
Extra-Long Low-Profile Phillips Screws Low heads with a PH recess for recessed covers and black chassis panels. Extra-Long Low-Profile Phillips Screws	Custom Extra-Long Machine Screws Family page: mixed heads, drives and finishes up to 2,000 mm. Custom Extra-Long Machine Screws	Extra-Long Hex-Head Dacromet Screws Long hex-head screws with a Dacromet coating for wet or outdoor assemblies. Extra-Long Hex-Head Dacromet Screws

Extra Long Socket Head Cap Screw FAQ

Order Extra Long Socket Head Cap Screws

How an extra long screw project runs from drawing to repeat delivery:

Each step is confirmed with you before the next one starts; the drawing revision from the first article is what repeat orders are checked against.